Your state’s most important highway in each range?

[webny99]

A humble stab at New York:

Single digits: Toss-up between NY 5 and US 9.
Tens: Could be NY 14/NY 15, but US 11 has the edge.
Twenties: US 20. NY 28 is definitely a competitor.
Thirties: NY 30
Forties: NY 49. Maybe US 44.
Fifties: NY 53
Sixties: US 62
Seventies: I'll go with NY 78 for now. Up for debate.
Eighties: () I-81
Nineties: I-99, because why not?

We could go further, but let's stop there. 

[jon daly]

Jp, you're not going with one of the US highways for the MIH in the single digit range? I suppose that they've all been superceded by an interstate; except US-7.

I'd go with  2 or 8 over 9.

Also, thanks for taking on Connecticut. I didn't have the time to give it serious thought.

[mrcmc888]

Tennessee:

1-9: TN-1, concurrent with US 70 and runs cross state
10-19: US-11, runs from Bristol to Chattanooga
20-29: I-24, connects Nashville with Chattanooga and St. Louis
30-39: US-31, major Nashville arterial
40-49: I-40, runs across the state from Memphis all the way to the Smoky Mountains
50-59: US-51, the way most rural West TN counties get to Memphis
60-69: I-65, Chicago one way, Mobile the other, and runs right through Nashville
70-79: I-75, connects Knoxville, Chattanooga and the Tri-Cities with Atlanta and Detroit
80-89: I-81, rises just outside of Knoxville and is the way most travelers use to get to the ski resorts in West Virginia as well as DC, Baltimore, Philly and NYC
90-99: TN-96, long bypass of Nashville and major arterial for farming communities just south of it

[SCtoKC]

I'm going to do my home state of South Carolina.

1-9: SC 9
10-19: US 17
20-29: I-26
30-39: SC 31 - Potential future I-74.
40-49: SC 41
50-59: US 52
60-69: SC 65 - Tough one, because none in this range stand out.  SC 65 is Ocean Boulevard in North Myrtle Beach.
70-79: US 76 (or I-77)
80-89: I-85
90-99: I-95
100s: US 178
200s: US 278
300s: I-385
400s: US 401
500s: US 501
600s: US 601
700s: US 701
800s: SC 823
900s: SC 917

[jemacedo9]

A humble stab at New York:

Single digits: Toss-up between NY 5 and US 9.
Tens: Could be NY 14/NY 15, but US 11 has the edge.
Twenties: US 20. NY 28 is definitely a competitor.
Thirties: NY 30
Forties: NY 49. Maybe US 44.
Fifties: NY 53
Sixties: US 62
Seventies: I'll go with NY 78 for now. Up for debate.
Eighties: () I-81
Nineties: I-99, because why not?

We could go further, but let's stop there. 

10's I'd go with NY 17 as long as it's mainly co-signed w/ I-86, and especially the Quickway portion, over US 11 or NY 14 or NY 15
80's I'd go with I-87 over I-81, because NY City - Albany - Northway > Binghamton - Syracuse
90's I'd go with I-90

[vdeane]

I'd go with US 9 for single digits.  It's the primary arterial east of the Hudson, whereas NY 5 is close to the Thruway for its entire length.

[wriddle082]

South Carolina

1-9:  I’m really struggling between US 1 and SC 9, but I’m thinking 9 has the edge since it’s not supplanted by any interstates and it stays close to most of the northern border.
10-19:  US 17
20-29:  I-26
30-39:  I’d say SC 34 since it’s fairly long going from Greenwood to Dillon.  But also SC 31 because it’s an important freeway bypass of a bypass of Myrtle Beach, which could one day be an interstate.
40-49:  Either SC 41 because it’s long or SC 49 because it serves suburban Charlotte.  SC 48 is also important since it runs along Columbia’s Assembly Street and passes by the SC State House and USC.
50-59:  US 52
60-69:  I’ll go with SC 64.
70-79:  I-77, but SC 72 gets honorable mention due to its improvements b/w GA and Clinton.
80-89:  I-85, duh!
90-99:  I-95, also duh!
100s: either US 123 because it goes through Clemson, or SC 151 since it’s all four lanes from Pageland to Darlington and is an important piece of an improved link b/w Charlotte and Florence.
200s:  going with US 278 because it connects I-95 with Hilton Head Island.
300s:  IMO it’s literally a three way tie b/w US 301, US 321, and I-385.
400s:  This one is tough.  I really don’t think it’s US 401 so I’m going with SC 460 since it’s a new route and bypasses Fort Mill.
500s:  pretty sure it’s US 501, but I-526 is also important.  Hmmm...
600s:  All I can think of is US 601 but I’m thinking there could be a better one?
700s:  I guess US 701, but maybe SC 768 because it’s a shortcut from I-77 to US 76/378 towards Sumter.  Or SC 703 going from the foot of the Ravenel Bridge through Mt. Pleasant to Sullivan’s Island.
800s:  wow, I can’t even think of any SC primary routes in the 800s
900s:  SC 901, which is an underrated alternate route to I-77 from northern Fairfield County to the outskirts of Rock Hill.

I’ll try to do Tennessee later.

[Max Rockatansky]

Starting California:

1-9

-  I'd say probably I-5 given the length traveled and through route from San Diego to L.A.  I'd argue that 1 is pretty up there as well given the tourism value in segments like Big Sur, the Devil's Slide, and North Shore Highway.  I-8 is important but that drops off considerably east of San Diego given the routing through the low parts of the Sonoran Desert.

10-19

-  Really it's hard to argue I-15 with the San Diego-Inland Empire-Las Vegas Connection, I-10 is close with the Los Angeles-Phoenix connection.  14 being part of the old US 6 corridor is important in terms of a desert connector.  17 spawned various 3d Interstates and still is an important Bay Area Highway.

20-29

-  I'd say 25 given it is essentially the main through road for the majority of San Benito County along the Airline Highway.  CA 25 has a National Park connection with Pinnacles at CA 146.  20 is a pretty lengthy route but isn't essential in terms of getting over the Sierras.  24 probably would have won this one before it was butchered by 3d Interstates.

30-39

-  I was originally going to say 33 but I decided on 36 instead.  36 essentially traverses some the length of the state in some really rural regions and is an all-year pass at the boundary of the Cascades/Sierras. 

40-49

-  I-40 is the cliche pick but 41 is more important to California as a whole.  41 is a major freeway in the Fresno Area and the most common access point for Yosemite National Park.  41 also is a major connector to the coast via the Diablo Range.  I-40 is surprisingly light on traffic and doesn't connect to much except ghost towns in-state wise.  46 is a major Central Valley-Coastal connector as part of the former US 466 corridor.  49 is an all-year pass of the Sierras and traverses much of the traditional California Gold Country as a tourism route.

50-59

-  US 50 is an all-year pass in the Sierras but 58 is way more practical for said purpose which is reflected in the traffic count.  58 east of 99 to I-15 pretty soon will be at least a four-lane expressway all the way which will make it even more of a favored route for commerce and travel.

[Alps]

I'm going to attempt NJ...

0-9: US 1
10-19: 18 may get the edge; 17 is pretty close
20-29: 21, 22, 24, 27 all maybe??!!  There's so many 2x routes near NYC that all are similarly important
30-39: 33, but again, see above.
40-49: US 46
50-59: 55
60-69: 66
70-79: I-78, but 70, 71, 72, 73 and I-76 could all easily come in 2nd.
80-89: I-80
90-99: I-95

1-9: Concur
10-19: I would argue 17 is more essential to Bergen County than 18 is to Monmouth.
20-29: Definitely not 27. I'm leaning 24 based on overall usage - 21 would win if it stayed a freeway through Newark.
30-39: I would select 31. It serves a major role in a corridor with no other roads. 33 is close, but parts of it are less important. You could also argue 35...
40-49: Concur, though 40 and 47 are close.
50-59: Concur
60-69: Concur
70-79: I would almost rank 70 over 78 just because of how important it is. If 78 goes down, you have 22 (or at least 173). If 70 goes down, there's nothing.
80-89: Concur
90-99: Concur
100-199: Just for fun. 139 earns my nod over I-195 because of how crucial a link it is.
200-299: A lot of important 2xx routes, but I'd vote for I-287. So congested all over.
300-399: US 322
400-499: NJ 444 (Garden State Parkway)
500-599: (NJ county system) A lot of good choices... I vote 501 but you could argue 508, 510, 517, 535, 539, or many others. A lot are just out nowhere despite being long and useful.
600-699: There is only I-676.
700-799: There is only NJ 700.

[roadman65]

Florida
0-9 I-4 but US 1 a close second being its the main road in the Keys
10-19 SR 15 (mostly cause its the secret number for US 17 north of Orlando)
20-29 US 27
30-39 SR 33
40-49 US 41
50-59 SR 50
60-69 SR 60
70-79 SR 70
80-89 SR 80
90-99 I-95
100-109 SR 105
110-119 SR 112
120-129 SR 121
130-139 N/A
140-149 N/A
150-159 N/A
160-169 N/A
170-179 N/A
180-189 N/A
190-191 N/A
200-209 SR 200
210-219 SR 212 ( US 90 east of I-95)
220-229 US 221
230-239 US 231
240-249 N/A
250-259 N/A
260-269 N/A
270-279 N/A
280-289 N/A
290-299 N/A
300-309 US 301
310-319 US 319

[Alps]

Bending rules for Rhode Island due to New England numbering conventions:
0-9 and 100-109: US 1, over 6 (because 101 and 6 split traffic)
10-19 and 110-119: RI 114, over 10
20-29 and 120-129: RI 122
30-39 and 130-139: RI 138
40-49 and 140-149: RI 146
50-59 and 150-159: RI 51 wins by default over RI 152, but neither is a great choice
60-69 and 160-169: RI 165 is the only one
70-79 and 170-179: RI 77
80-89 and 180-189: RI 81 is the only one, but at least it's decent
90-99 and 190-199: I-95
200+: I-295

[Alps]

Delaware (oh boy):
1-9: DE 1
10-19: US 13
20-29: DE 20; 24 a close second
30-39: DE 30
40-49: US 40
50-59: DE 54
60-69: DE 62 is the only choice
70-79: DE 71
80-89: DE 82 is the only choice
90-99: I-95
100+: US 301, with honorable mentions to I-295, US 113, and DE 896

[Max Rockatansky]

California continued:

60-69

-  Traditionally this would have been US 66 for obvious reasons.  Today CA 60 serves a completely viable alternate to I-10 in Metro L.A. and really should have remained US 60.  65 would have been pretty up there if the segments were ever connected together.  62 is a solid alternate to I-10 through the desert to Arizona but doesn't connect to much east of 29 Palms.

70-79

-  By far CA 70 through the Feather River Canyon which is a fairly easy all-year pass of the Sierras.  Previously CA 70 was part of US 40a and CA 24 prior to that.  74 and 78 merit some consideration due to their length.

80-89

-  I-80 is unquestionably the most important 2d Interstate in California with the Bay Area connection east over Donner Summit to Nevada.  85 is a fairly important freeway but 88 I think ranks up there higher due to it being an all-year pass in the Sierras via Carson Pass and an alternate to US 50.  89 is a great tourism route with Lassen Volcanic National Park, Lake Tahoe, Mount Shasta, and Monitor Pass.

90-99

-  99 takes the win by far and still should be a US Route.  CA 99's freeway segment is the longest in the country that isn't park of the Interstate system.  Surprisingly US 95 doesn't really offer all that much in terms of being important to California as a whole due to the rural desert alignment, I'd say AZ 95 carries more weight.  US 97 connects to some important eastern areas in Oregon but not much in California.  91 still carries a lot of weight as a limited access facility.  96 and 94 are important regional routes that have substantial length.

100-109

-  By far US 101 considering it's length and importance as a travel corridor between Los Angeles to San Francisco.  Said segment of US 101 doesn't even have a traffic light between Los Angeles and San Francisco anymore.  I-105 doesn't do much for me and I tend to look as short routes no matter what type as not all that important on a state-wide scale.  CA 108 is a pass of the Sierras but is seasonal and not very practical with 26% grades.

110-119

-  CA 110/I-110 is a pretty important route between Pasadena and Long Beach...doesn't hurt it was part of US 66.  CA 111 connects some significant regions in the Sonoran Desert.  =

120-129

-  I'd say CA 120 given the connection to Yosemite and a seasonal pass of the Sierras on the implied Tioga Pass route.  CA 126 has a major impact connecting the Ventura to the Los Angeles area but it can't outweigh a Trans-Sierran route to a National Park IMO.  CA 127 connects some really rural parts of the Mojave Desert near the Nevada State Line and essentially is a connector to Death Valley National Park. CA 128 has a huge length in some really rural mountain areas north of the Bay Area.

130-139

-  I'm going to go with CA 132 given the corridor connects I-5 to CA 99.  It doesn't hurt CA 132 can be used as a way to reach CA 132 heading east towards Yosemite.  CA 134 is an important freeway in the Los Angeles area.  CA 138 is continually touted as some future corridor of importance in the Mojave but really parts of it should be CA 2 still.  CA 139 connects some really rural areas to major routes in the Cascades.

140-149

-  I'm going to give this one to 145 given the connection between the I-5 and CA 99 corridors.  CA 140 probably would beat it in my book if the Fergusson Slide in the Merced River Canyon ever gets fixed, personally this is my favored route out of Yosemite.  CA 146 exists in two segments connecting Pinnacles National Park.

150-159

-  CA 152 over Pacheco Pass is a huge connector from the Central Valley to the Bay Area.  CA 150 connects some rural areas north of Ventura that don't have much access otherwise.  CA 156 essentially is the primary route from the Monterey Peninsula to US 101 and Pacheco Pass.

160-169

-  CA 168 is an important freeway in Fresno which connects to really nice tourist areas in the western Sierras.  Eastern CA 168 is a rural connector to some derelict parts of Nevada.  CA 160 is an important corridor in the Delta Area and CA 163 is a major freeway connecting downtown San Diego to I-8.  CA 166 connects the Central Valley to the coast on a beautiful routing through the Cuyama Valley.  CA 167 has become a favored trucking route from US 395. 

170-179

-  CA 178 takes this one considering Walker Pass is a viable all-year pass in the Sierras.  CA 58 west of Bakerfield used to part of CA 178, really it should be a state-wide route.

180-189

-  CA 180 is a major freeway in Fresno and connects to Kings Canyon National Park.   180 would even be more important if it had a completed connection to CA 25.

190-199

-  Really I'd say CA 198 given it connects US 101, I-5, CA 99 and Sequoia National Park.  CA 190 would have more weight if the Trans-Sierran Pass was completed but it is the primary route through Death Valley National Park.  US 199 connects US 101 to I-5 but really is extremely rural.

[Max Rockatansky]

Continuing with California:

200-209

-  Not much in this ban, so pretty much I-205 by default.

210-219

-  Really I think I-210 over I-215 probably would take the win here considering it absorbed CA 30.

220-229

-  CA 223 is the most substantial route in this ban and connects some major corridors like; I-5, CA 99, and CA 58.  The climb up to CA 58 is actually pretty scenic.

230-239

- CA 237 is a major freeway I personally would pick it over I/CA 238.  CA 236 connects CA 9 to Big Basin State Park which is among the higher tier in the state. 

240-249

-  245 personally is among my favorite drives in the state and essentially is an alternate between Kings Canyon and Sequoia National Parks over the Generals Highway.  CA 241 is an important limited access facility but doesn't serve much outside of Metro Los Angeles.  CA 243 connects some mountainous routes to I-10.  CA 247 connects I-40 to CA 62 and is part of a Interstate bypass route I take to Arizona.

250-259

-  CA 254 because its the Avenue of the Giants and a former segment of US 101.

260-269

-  CA 262 connects a couple Interstate routes.  CA 261 is a toll road in the Los Angeles area.  CA 267 connects I-80 directly south to Lake Tahoe.

270-279

-  I'd take CA 270 given it connects US 395 to Bodie State Park.

280-980

-  US 395 wins this one given it is the major north/south route on the eastern flank of the Sierras and Mojave Desert.  I-280 probably would take the win in terms of 3d Interstates given it essentially the twin-connecting route from San Jose to San Francisco.  CA 299 connects numerous US Routes and traverses the state.  I-580 is hugely important connecting the Central Valley to the Bay Area.  I-405 is up there but personally I don't think it really has a much purpose beyond being traffic jam hell in the Los Angeles area.

[jon daly]

Steve or anyone else, I should probably know this, but what is different about New England numbering conventions?

[pianocello]

Iowa:

1-9: IA 5. It's the only single-digit state route that has significant expressway sections, although IA 2, IA 3, US 6, and IA 9 go across the entire state.
10-19: US 18?
20-29: US 20
30-39: I-35, although honorable mentions can be given to US 30 and US 34
40-49: IA 44. Not much to choose from here.
50-59: IA 58
60-69: US 61
70-79: US 71
80-89: I-80
90-99: IA 92

The state highway numbers get kinda sparse past 100.

[webny99]

A humble stab at New York:
Single digits: Toss-up between NY 5 and US 9.
Tens: Could be NY 14/NY 15, but US 11 has the edge.
Twenties: US 20. NY 28 is definitely a competitor.
Thirties: NY 30
Forties: NY 49. Maybe US 44.
Fifties: NY 53
Sixties: US 62
Seventies: I'll go with NY 78 for now. Up for debate.
Eighties: () I-81
Nineties: I-99, because why not?

10's I'd go with NY 17 as long as it's mainly co-signed w/ I-86, and especially the Quickway portion, over US 11 or NY 14 or NY 15

Whoops. I tend to think of it exclusively as I-86 west of Binghamton. Including just Binghamton to I-87, despite it's status as an expressway, I think a case could still be made for US 11.

80's I'd go with I-87 over I-81, because NY City - Albany - Northway > Binghamton - Syracuse

Yeah, probably true, although I'd rather be biased towards upstate than downstate. 

90's I'd go with I-90

Knew somebody would catch that one.

[plain]

40-49: US-48 (Also considered: VA-40, VA-48)

I think VA 40 is waaaaaayy more important to Virginia than US 48 is

[froggie]

^ Agreed.  US 48 in Virginia is basically an afterthought.  Though one could make an argument that VA 42 has more import than VA 40.

[ftballfan]

I've seen two for Michigan, but I decided to do my own (mostly the same).

0-9: M-1, but an argument could also be made for M-6
10-19: US-10 and M-10 share, since they once were the same route
20-29: US-23, especially considering it's quicker than I-75 from Flint to Toledo (that puts it ahead of M-25 or M-28)
30-39: US-31
40-49: M-46, just slightly ahead of US-41
50-59: M-55, ahead of M-50 (pre-freeway, M-50 would have won)
60-69: I-69
70-79: I-75
80-89: M-85 (very tough to decide between M-85 or M-89)
90-99: I-94, just ahead of I-96
100-119: M-117
120-139: M-120
140-159: M-153
160-179: M-179 by default (despite it having multiple four-way stops with local roads)
180-199: I-196
200-249: M-231 (while a little out of the way, it does serve as a Grand Haven bypass whenever traffic is backed up on US-31, which is common)
250-299: I-275
300-499: I-496, ahead of I-475 due to Lansing being the state capital and not the wasteland that Flint is
500+: I-696

[DandyDan]

Iowa:

1-9: IA 5. It's the only single-digit state route that has significant expressway sections, although IA 2, IA 3, US 6, and IA 9 go across the entire state.
10-19: US 18?
20-29: US 20
30-39: I-35, although honorable mentions can be given to US 30 and US 34
40-49: IA 44. Not much to choose from here.
50-59: IA 58
60-69: US 61
70-79: US 71
80-89: I-80
90-99: IA 92

The state highway numbers get kinda sparse past 100.

I can agree with most of your selections. I-29 can be it for the 20's if you consider the national scheme of things. The 40's and 50's don't offer much, but I can see IA 57 outranking IA 58, if only for length and the fact it used to be US 20.

As for 100+ highways, I will go with US 218, but if you want to make it I-380 or I-235, so be it.

[vdeane]

80's I'd go with I-87 over I-81, because NY City - Albany - Northway > Binghamton - Syracuse

Yeah, probably true, although I'd rather be biased towards upstate than downstate. 

Albany is upstate!  And yeah, the Northway gets a LOT more traffic than I-81, especially in tourist season; it has one of the longest continuous 6+ lane sections of road in the state (55 miles from I-90 through Lake George) for a reason.

[hbelkins]

^ Agreed.  US 48 in Virginia is basically an afterthought.  Though one could make an argument that VA 42 has more import than VA 40.

I wouldn't exactly say 42 has "import," although it is a scenic drive (I've clinched all three segments).

[Sctvhound]

South Carolina

1-9:  I'm really struggling between US 1 and SC 9, but I'm thinking 9 has the edge since it's not supplanted by any interstates and it stays close to most of the northern border.
10-19:  US 17
20-29:  I-26
30-39:  I'd say SC 34 since it's fairly long going from Greenwood to Dillon.  But also SC 31 because it's an important freeway bypass of a bypass of Myrtle Beach, which could one day be an interstate.
40-49:  Either SC 41 because it's long or SC 49 because it serves suburban Charlotte.  SC 48 is also important since it runs along Columbia's Assembly Street and passes by the SC State House and USC.
50-59:  US 52
60-69:  I'll go with SC 64.
70-79:  I-77, but SC 72 gets honorable mention due to its improvements b/w GA and Clinton.
80-89:  I-85, duh!
90-99:  I-95, also duh!
100s: either US 123 because it goes through Clemson, or SC 151 since it's all four lanes from Pageland to Darlington and is an important piece of an improved link b/w Charlotte and Florence.
200s:  going with US 278 because it connects I-95 with Hilton Head Island.
300s:  IMO it's literally a three way tie b/w US 301, US 321, and I-385.
400s:  This one is tough.  I really don't think it's US 401 so I'm going with SC 460 since it's a new route and bypasses Fort Mill.
500s:  pretty sure it's US 501, but I-526 is also important.  Hmmm...
600s:  All I can think of is US 601 but I'm thinking there could be a better one?
700s:  I guess US 701, but maybe SC 768 because it's a shortcut from I-77 to US 76/378 towards Sumter.  Or SC 703 going from the foot of the Ravenel Bridge through Mt. Pleasant to Sullivan's Island.
800s:  wow, I can't even think of any SC primary routes in the 800s
900s:  SC 901, which is an underrated alternate route to I-77 from northern Fairfield County to the outskirts of Rock Hill.

I'll try to do Tennessee later.

Agree with most of yours. SC 61 could also be the most important in the 60s, since it connects all the historical plantations and is a major route in Charleston.

[Quillz]

CA, Pt. 2

100-109: Easy choice here, it's the 101. The longest highway in the state, connects LA to the Bay Area, historically also went to San Diego.

110-119: Both 110 and 118 are important within the Greater LA Area. 110 is one of the oldest freeways and closest to Downtown LA, while 118 is an important Oxnard-San Fernando connector, with the eastern half a freeway through the Simi and San Fernando Valleys. I'd rank 113 as important, too. A short freeway segment between Davis and Woodland and can be used as a bypass of Sacramento (although the 505 is generally better).

120-129: 120 would be my pick. A freeway through a portion of the Central Valley, then climbs the Sierra foothills and eventually Tioga Pass through Yosemite. Then has a segment through the Eastern Sierra, finally ending at US-6 near the Nevada border. But other important regional highways would include 126, 127, and 128.

130-139: 134, 138, 139 seem equally important to me. 138 isn't very long, but is an all-freeway connection between 101 and 210 (i.e. the Ventura and Foothill Freeways). Burbank, Glendale, Pasadena are all directly on the freeway's alignment. 138 is an important corridor for the high desert area, mainly Palmdale, and is often utilized as a way to either get to Vegas (via I-15 at Cajon Pass) or into the San Bernardino Mountains (beyond Cajon Pass). It's probably used more for diverting traffic onto the 15 or 18, but is still very well traveled. And 139 connects Susanville, CA to Klamath Falls, OR. Other than taking US-97 directly, 139 is the only California route that leads directly into Central Oregon and ultimately its larger cities (such as Bend).

140-149: 140 is really the only significant route I can think of (several numbers in this range aren't even assigned). Like 120, 140 leads into Yosemite, although its probably used less than either the 41 or 120. Beyond that, it is another route across the San Joaquin Valley and provides access to I-5.

150-159: 154 would be my pick. Originally part of a longer 150, 154 is the San Marcos Pass Road and is often used as an alternate to 101. It skips the Gaviota coast entirely and gives alternate access to Solvang (a popular tourist town) and direct access to Los Olivos (one of the important Santa Barbara Wine Country towns). It would be more useful if it could bypass Santa Barbara entirely (doing this requires taking 192 in addition).

160-169: Everything in this range is pretty regional in nature. I'd probably pick 168 only because both non-contiguous portions lead to popular spots in the Sierra. And in theory, if the two portions were connected, would provide a very nice trans-Sierra route that would provide alternate access to Bishop and the Mammoth Mountain Ski Area. But there is also 166, historically one of the earlier connections between the Central Coast and the Central Valley. But today, it's more of a scenic alternate than anything else, following the Cuyama River.

170-179: 178 is a pretty easy choice here. Historically, nearly crossed the entire state from the Central Coast to east of Ridgecrest. Has a second segment in Death Valley that crosses into Nevada, so a theoretical connection between the portions would make it one of the few west-east state routes to cross a border. Of course, nowadays it begins in Bakersfield, but it isn't any less important. It's generally considered the southernmost Sierra pass, and while fairly low, also makes it open year-round. Most motorists from the LA area would just use the 14 -> 395 to reach the Sierra, but for Central Valley motorists, 178 is a good choice.

180-189: Another range of mainly regionally-important routes. 180 is probably my pick, being a freeway through Fresno and also giving access to both Sequoia and Kings Nat'l Parks (the former via 198/Generals Highway, the latter directly). 186 and 188 are very short routes (maybe a mile at most), but they reach the international border with Mexico and thus are significant for that reason alone (both border stations are very busy).

190-199: The eastern half of 190 would probably be my pick. It is generally how most LA motorists would reach Death Valley, since it lets them avoid the Inland Empire traffic on I-15, followed by frequent backups near Barstow and Baker. The wester half is less significant, and while there is no official connection between the two, there is a series of forest routes that make an unofficial connection and are open through the winter. 198 is another important route, but its mainly used to reach Sequoia Nat'l Park, so only the segment east of Visalia will generally see much traffic. And finally, 199 is a US highway, but itself is pretty little traveled, although its probably the best connection from the North Coast to Central Oregon between CA-299 and OR-42.