Hierarchy of highways in your county

[thspfc]

Rank your county's highways based on importance their importance to the county.

For Dane County WI:

T1. I-39 and I-90 (concurrent for entire length in county)
3. I-94
4. US-12
5. US-151
6. US-18
7. US-14
8. WI-30
9. US-51
10. WI-19
11. WI-113
12. WI-78
13. WI-73
14. WI-69
15. WI-138
16. WI-92
17. WI-106
18. WI-89
19. WI-188
20. WI-104

[Max Rockatansky]

Fresno County

-  CA 99
-  CA 41
-  CA 180
-  CA 168
-  I-5
-  CA 33
-  CA 198
-  CA 43
-  CA 145
-  CA 269
-  CA 63
-  CA 201
-  CA 245

[NWI_Irish96]

For Lake County, IN, I included a few unnumbered routes that are actually more important than some of the numbered routes

Tier I: Major freeways
1) I-80/94
2) I-65

Tier II: Just slightly less major because tolled
3) I-90/Indiana Toll Road

Tier III: Minor freeways & Major arterials:
4) US 30
5) US 41
6) IN 912

Tier IV: important arterials
7) US 20
8) US 12
9) IN 53
10) US 231

Tier V: major local roads & minor arterials:
11) IN 152 (connects the US 41 and US 12/20 segments of Indianapolis Blvd)
12) US 6/Bus US 6/Ridge Road (main thoroughfare in Munster/Highland/Lake Station)
13) Calumet Ave (unnumbered section between I-80/94 and US 30, main thoroughfare in Munster/Dyer)
14) IN 2
15) IN 55
16) 45th St/45th Ave

Tier VI: locally important routes
17) IN 51
18) IN 312
19) IN 130

[TheHighwayMan3561]

Hennepin County, MN

1. (tie) I-94 and I-35W
I-494
MN 62
MN 100
US 169
I-394
US 212
MN 610
US 12 (outside of 494)
MN 77
MN 55
MN 5
I-694 (virtually all of the Hennepin County portion is duplexed with I-94)
MN 101 (just being a freeway isn't always that important)
MN 47/65 (the designations matter less than their street names)

Dead Last: MN 121

[1995hoo]

Fairfax County, Virginia:

1. I-495 (the Capital Beltway)
2. I-95/I-395
3. I-66

This is where it then gets a little tougher. Tysons Corner has become Fairfax County's "downtown" and almost a small city unto itself, so I decided to consider the major routes that serve it to be the next on the importance list. I put VA-7 higher on the list simply because on the whole it seems like a more important commuter road than VA-123 does. I put VA-123 higher than VA-267 because 123 runs all the way across Fairfax County from south to north.
4. VA-7
5. VA-123
6. VA-267 (the Dulles Toll Road; not counting the Airport Access Road)

Then the Fairfax County Parkway is the only significant route that connects the county's northwestern end to its southeastern end; before it was constructed, you had to go in to the Beltway or use a bunch of connecting routes:
7. VA-286
8. VA-289 (stub route that serves the important role of connecting to the Springfield transit hub)

The next two routes overlap through the City of Fairfax, which isn't part of Fairfax County. It was a bit of a tossup which to list first; I listed US-50 first because I think the part inside the Beltway is more important as a commuter route.
9. US-50
10. US-29

The next ones are low as they are because they serve the extreme ends of the county, whereas the ones above serve more of a range of locations; also, south of the Beltway the GW Parkway and VA-235 serve as an alternate to US-1.
11. US-1
12. George Washington Memorial Parkway
13. VA-235 (connects to the GW Parkway)
14. VA-28

I don't think all the secondary routes merit mention, but the next one is a significant exception, as the part west of I-95 is a very significant arterial. At one point, VDOT explored seeking federal funding to improve it.
15. Secondary Route 644

The next two are critical east-west routes.
16. Secondary Route 620
17. VA-236

The next one is more important in Arlington than it is in Fairfax County.
18. VA-244

The next three are relatively significant connectors between parts of the county that can be more direct than the Interstate.
19. Secondary Route 617 (Backlick Road; connects Springfield and Annandale)
20. Secondary Route 650 (Gallows Road; connects Annandale and Tysons Corner)
21. Secondary Route 638 (connects Route 620 and Route 644 and is the last such connection before the Beltway cuts off most direct routes)

This last one is the most significant route serving the Clifton area, the far southwestern part of the county.
22. Secondary Route 645.

[JayhawkCO]

Arapahoe County, CO

1) I-25
2) I-225
3) I-70

It's weird to have a 3di higher than a 2di, but within the county, I-70 only hits the boonies.

4) US85
5) US285
6a) US40
6b) US287

US40 and US287 are concurrent on Colfax.

8) US87

In theory, could be higher, but it's concurrent with I-25 so if it didn't exist, it wouldn't matter.

9) CO83
10) CO30
11) CO88
12) CO177

All of these are important roads that carry a ton of traffic.

13) CO75

Don't really know why this is a state highway, but at least it's in the burbs.

14) CO470

It's very important for the metro, but the actual portion that's in Arapahoe County doesn't even have an exit, so it gets demoted.

15) CO79

Rural connector between towns.

16a) CO36
16b) CO40

I-70 frontage roads that used to be US36 and US40

[GaryV]

Oakland Co, Michigan:

I-75
I-696
I-96
M-59
M-1
US-24
M-5
I-275 *
M-10 **
M-39 **
M-150
M-24
M-15

* - this one would be higher, except it only runs from an exit at 8 Mile Rd on the county's southern border to its terminus at I-696.

** - these only because of their continuations into Wayne Co.

[Great Lakes Roads]

La Porte County, IN:

1. I-94
2. I-80/90 (Indiana Toll Road)
3. US 30
4. US 20
5. IN SR 2
6. US 12
7. US 35
8. US 421
9. US 6
10. IN SR 39
11. IN SR 4
12. IN SR 8
13. IN SR 212
14. IN SR 104

[jlam]

Weld County, CO:

1) US 85
2) US 34
3) I-25
4) SH 257
5) US 87
6) SH 392
7) SH 60
8) I-76
9) SH 119
10) US 6
11) SH 52
12) SH 66
13) SH 56
14) SH 14
15) SH 263
16) SH 71
17) SH 144

This was hard as a large chunk of every road in the county is rural. Not much here.
Tell me if I missed anything

[JayhawkCO]

This was hard as a large chunk of every road in the county is rural. Not much here.
Tell me if I missed anything

Missed CO402 and CO79. Technically CO263 doesn't exist anymore either.

[gonealookin]

Douglas County, Nevada:

1.  US 50 (for tourism, connecting Reno and Carson City with South Lake Tahoe)
2.  US 395 (#1 for county residents for service to Minden and Gardnerville in Carson Valley)
3.  NV 207 (connects Tahoe to Carson Valley)
4.  NV 28 (completes the tourist loop around Lake Tahoe)
---
Main roads in Carson Valley:
5.  NV 88 (also continues into California)
6.  NV 206
7.  NV 756
---
8.  NV 208 (connects to Lyon County and is part of the most logical route to Las Vegas)
9.  NV 759 (stub to the local airport)
10.  NV 757 (minor connector in Carson Valley)
11.  NV 760 (stub from US 50 to USFS' Nevada Beach)
---
999.  NV 705, an orphaned piece of old US 50 which is really just part of a glorified driveway to some residential properties within the Carson City limits

[Ted$8roadFan]

Middlesex County, Ma

I-90 (Mass. Pike
I-95
I-495
I-93
US 3
MA 9
MA 2
MA 28
US 20
MA 27
MA 126
MA 16
MA T2

[skluth]

Riverside Co CA

I-10
CA 60
CA 91
I-15, I-215 tied
CA 79
CA 74, CA 86, CA 111 tied
US 95
CA 71
CA 62
CA 243
CA 371
CA 177

[Techknow]

San Francisco city and county:

I-80 - west terminus of the 2DI
US-101 - connects the city with many other both big and small
I-280 - a bypass of US-101 to San Jose with beautiful scenery and little traffic nowadays but only if your commute can take advantage of it. Otherwise you can get to the Embarcadero easily

The rest of the state highways are surface streets

CA 1 - one of two arterials in the Sunset District (the other being Sunset Blvd) and carries a lot of traffic
CA 35 - Has HAWK signals and leads to the Zoo I guess.
CA 82 - Very short before it enters Daly City

[SkyPesos]

Hamilton County, OH:

- I-75
- I-71
- I-275
- US 52 (incl I-74)
- OH 126
- US 50
- OH 562
- US 127
- US 22/OH 3
- US 27
- US 42
- OH 4
- OH 264
- OH 561
- OH 125
- OH 32
- OH 128
- OH 747
- I-471

[dgolub]

Nassau County, NY:

1. Long Island Expressway (I-495)
2. Northern Parkway
3. Southern Parkway
4. Meadowbrook Parkway
5. Wantagh Parkway
6. Seaford-Oyster Bay Expressway (NY 135)
7. Sunrise Highway (NY 27)
8. Jericho Turnpike (NY 25)
9. Northern Boulevard (NY 25A)
10. Hempstead Turnpike (NY 24)
11. Hillside Avenue (NY 25B)

Some of the above are really ties (e.g. NSP vs. SSP).

[SEWIGuy]

Brown County, WI

I-41
I-43
WI-172
US-41 (north of I-41)
WI-29
WI-57
WI-54
WI-32
WI-96
US-141 (duplexed with other highways for its entire length except a short stretch on Green Bay's north side)

[tchafe1978]

Lafayette County, WI

1. US 151
2. CTH XX
3. WIS 23
4. WIS 11
5. WIS 81
6. WIS 126
7. WIS 78
All other county highways

Lafayette County is very rural so outside of US 151 and CTH XX most highways are very lightly trafficked.

[ilpt4u]

Jackson County, IL

1) IL 13
2) US 51
3) IL 127
4) IL 149
5) Old IL 13
6) IL 4
7) IL 3
8) Old US 51
9) IL 151

[nsexpeditions]

Mecklenburg County- NC

I-77/US21
I-85
I-485
I-277
US74
Billy Graham Pkwy
NC 73
NC16
––––– all above are freeways/expressways or have sections of them
NC24––weird sub highway sub drive
NC49––main city road that lots use
NC160––road for the west side of town
US29––road for the east side of town
US521––suburban boulevard that goes into SC
NC51––neighborhood connecting road in south Charlotte

[adventurernumber1]

For Whitfield County, Georgia, Interstate 75, by far the most important road for through travelers, also is likely the most important road for the county as well.

US 76 is actually concurrent with US 41 through most of the county, whereas US 41 has more independent mileage. Even so, US 76's independent mileage in the county does consist of an important divided highway. I'd say have them tied for # 2. 

# 3 is definitely GA 71, given that it is four-lanes most of the way through the county and is an important corridor (looking outside the county, the main route for Dalton-Cleveland traffic as well).

# 4 would be GA 52, a very important road through the city of Dalton, though concurrent with US 76 in the eastern part of the county.

Then afterwards would be GA 2, GA 201, GA 286, and all the similarly important roads in the county as well as arterials through Dalton.

[CoreySamson]

I like the tier system for this:

Brazoria County:

Tier A:
1. TX 288
It's the major freeway that connects the county to Houston and the coast. Most deservedly #1.

Tier B:
2. TX 35
It passes through 3 of the county's biggest cities and has a lot of mileage through here.

Tier C:
3. TX 6
4. TX 36
5. TX 332
6. TX 288 BUS B
The rest of the county's state highways are moderately important. 6 and 36 are arguably more important outside of the county, which gives them the nod over 332.

Tier D:
7. FM 518
8. FM 521
9. FM 2004
518 is one of the busiest routes in the county, 521 is a great 288 alternative, and 2004 is the preferred route between Galveston and Brazosport.

Tier E:
10. FM 528
11. FM 1128
12. FM 2234
13. FM 865
14. FM 523
15. TX 35 BUS E
16. TX 35 BUS C
528, 1128, 2234, and 865 are included here because of the development on them rather than their length. 523 is another great 288 alternative. Plus 35 has a couple business routes.

Tier F:
17. FM 1462
18. FM 524
19. FM 1495
20. FM 2611
21. FM 1459
22. FM 2917
23. FM 2403
All of these are unimportant rural FM routes.

[nwi_navigator_1181]

Porter County, IN.

Tier I: The Majors
I-94 (keeping close to the lakeshore and National Park, and being one of only two direct access routes to Michigan)
The Indiana Toll Road - while it has only two ramps serving Porter County (Willowcreek Road and Indiana 49), those two exits serve as access points to most major areas. In the case of Indiana 49, you have access to the rest of Porter County's major sectors if you know what you're doing.

Tier II: The Arterials
US 20 - Four lanes the entire way through and the clear go-to route if I-94 or the Toll Road isn't your cup of tea. The integral path between Gary and South Bend.
US 12 - The more scenic/industrial route between Gary and Michigan City, closely following US 20 until the Porter-Laporte County line. Access to the Steel Mills, South Shore stations, National Park, and beaches for miles. May get closer to equal footing to US 20 once double-tracking of the South Shore Line is complete.
US 30 - The closest to being a "freeway"  for Central-Southern Porter County. A divided highway the entire way through, it really picks up in importance for those looking to cut through Indiana with little fuss once east of Indiana 49.
US 6 - While not as "busy"  as the above US routes, it's still a viable path for those looking to access towns and cities off the beaten path. Really shows its importance in Portage, serving as the major artery of southern Portage.
Indiana 49 - While it may not be as important south of the Porter County Fairgrounds, it's a major player from US 30 northward, switching between freeway and expressway. Within 10 miles, you have access to US 30, Indiana 2, US 6, the Toll Road, I-94, US 12/20, the Dunes National Park, and the Dunes Park South Shore Station.
US 231: This road has a quick jump through Porter County, but still has importance. It's the only north-south US highway in Porter County and is the link point in Hebron for Indiana 2 and Indiana 8. Short, but sweet.

Tier III: The Major Locals (includes unnumbered roads)
Indiana 2 - the diagonal route from Hebron to just west of...Westville. This road covers a wide swath of Porter County and is a nice alternative to the roads that have supplanted it.
Indiana 8 - Another quiet route that covers Hebron, Kouts, and point beyond. Not known for a lot of traffic.
County Road 100 S (known as 109th Avenue in Lake County) - Accessing Crown Point, Winfield, Lakes of the Four Seasons, and - ultimately - Indiana 2. The only other route that connects Broadway to Indiana 2 besides US 30 and US 231. A good alternative if you have time to burn.
Indiana 149: Major connection between US 12 and Indiana 130, with access to the steel mills, US 20, and US 6. No interstate access, which isn't all that problematic.
Indiana 130 - A major commuter route between Valparaiso and Hobart, with access to the major expressways by way of Indiana 51. Still important despite being truncated to Indiana 149 in recent years.
Willowcreek-Crisman Road: the major arterial of Portage, whose importance will be greatly increased if/when the road extends to US 30. In its current form, it's purposeful from its current southern terminus to its connection to Indiana 249, including one of only two access points within the county to the Toll Road.
Central Avenue: connects eastern Portage to points as far west as Gary's west side. Would serve an even greater purpose if access to Hammond wasn't cut off at Cline Avenue.

Tier IV: Short, But Important (similar to the thread I started)
Indiana 520 - the only route between Indiana 49 and Indiana 212 that truckers can use to jump between US 12 and 20, and less than a quarter of a mile long. Going east, this road makes a difference between downtown Michigan City and the outer fringes. Coming from Michigan City, this road makes the difference between interstate, beachfront, industrial, and railway access. Almost the same as...
Indiana 249 - in a very short span, provides easy access to US 12, US 20, I-94, the Port of Indiana, and the Ogden Dunes South Shore Station. Doubles in value when coupled with the above mentioned Crisman-Willowcreek connection.

[Evan_Th]

Doing one of the counties where I grew up, not my current county, because it's got fewer highways.

ORANGE COUNTY, NC:

US 15-501 - Major artery in Chapel Hill, and its route to Durham.
NC 86 - Backbone of the county, connecting the three major towns.
I-85 - Major east-west road, connecting the county with the rest of the Urban Crescent.
NC 54 - Major road in Chapel Hill and Carrboro, plus part of the best route from Chapel Hill to Raleigh, plus an east-west rural route across the south county.
I-40 - Runs north-south across the county
US 70 - Parallels I-85
US 70 ALT - City streets in Hillsboro.
NC 57 - Rural road in the north county.
NC 49, NC 157 - Cut across the northern corners of the county; both insigificant in the county.

[webny99]

Posting this mostly as a placeholder: It should surprise no one that I wasn't happy with a subjective answer, so I'm working on an "importance factor" for each route in Monroe County using the average AADT of the route and the mileage within the county. It's a bit time consuming so it might take a few days before I have it posted - but an interesting exercise nonetheless and a good way to become better associated with the AADT volumes of the highways in my county.