One-county state highways

[golden eagle]

We have a few of these in MS:

MS 463 is entirely in Madison County
MS 468 and 471 are only in Rankin County
MS 467 runs through Hinds County from Edwards to Raymond
MS 67 runs from Biloxi to US 49 at Saucier, all in Harrison County
MS 603 & 604 run only through Hancock County

[NE2]

Florida has a lot. Off the top of my head: 3, 5A, 423, 424, 437, 438, 441, 482, 539, 540, 542, 544, 548, 551, 552, 553...

[corco]

Most of Wyoming's are intra-county

[CentralCAroadgeek]

Quite a lot of these in Northern California, especially in the Bay Area.
Monterey County
- 68
- 183
Santa Clara County
- 85
- 87
- 130
- 237
Alameda County
- 13
- 61
- 185
- 238
- 260
San Mateo County
- 109
- 114
Contra Costa County
- 242
Marin County
- 131

[Some_Person]

I'm sure they're very common if you really look into a lot of them. Off the top of my head I know there's PA 946 and 512 in Northampton County, PA, which is relatively small at 377 sq miles. There's also PA 222 in Allentown (Lehigh County) which was to be a part of US 222 that got denied, so there are probably a lot of intra-county state routes in multiple counties that exist for the same or at least similar reason, for example NJ 495

[kinupanda]

Offhand I can think of a few Texas examples... severely incomplete list follows:

• SH 10 and SH 26 in Tarrant Co.
• SH 57 in Smith Co.
• SH 151 and SH 218 in Bexar Co.
• SH 93 in Bowie Co.
• SH 40 in Brazos Co.
• Toll SH 255 in Webb Co.

Not sure whether most of these are in the more urban areas or if those are just the examples that came to my mind more readily. There are a few in relatively less populated areas, i.e., SH 51 in Hansford Co., but as expected many seem to connect two county seats.

Oh, of course, can't forget SH 165 in Travis Co.

[on_wisconsin]

Highway 30 is the only one I can think of off hand for Wisconsin. Minnesota has quite a few in the Cities area from what I can recall.

[xonhulu]

Quite a few in Oregon:

OR 3 Wallowa
OR 8 Washington
OR 11 Umatilla
OR 37 Umatilla
OR 38 Douglas
OR 39 Klamath
OR 46 Josephine
OR 51 Polk
OR 52 Malheur
OR 70 Klamath
OR 86 Baker
OR 103 Clatsop
OR 131 Tillamook
OR 201 Malheur
OR 205 Harney
OR 210 Washington
OR 212 Clackamas
OR 214 Marion
OR 217 Washington
OR 224 Clackamas
OR 228 Linn
OR 229 Lincoln
OR 233 Yamhill
OR 234 Jackson
OR 240 Yamhill
OR 281 Hood River
OR 282 Hood River
OR 331 Umatilla
OR 380 Crook
OR 402 Grant
OR 528 Lane
OR 569 Lane

I left off a few still-unsigned routes, but I think I got all the signed highways.

[bulldog1979]

For Michigan, you'd find (unsigned highways marked with an asterisk):

M-8
M-17
M-27
M-47
M-49
M-58
M-63
M-67
M-71
M-73
M-75
M-80
M-85
M-88
M-93
M-103
M-104
M-109
M-113
M-116
M-119
M-125
M-136
M-137
M-139
M-142
M-143*
M-149
M-150
M-154
M-155*
M-156
M-157
M-183
M-185
M-186
M-189
I-194
M-199
M-201
M-203
M-204
M-211
M-212
M-217
M-221
M-222
M-227
M-239
M-247
M-294
I-296*
M-311
M-331*
I-375
I-475
M-553
I-675

Most of the business loops and spurs in the state are single-county highways as well. The Michigan segment of US 8 exists in only one county, and the southern segment of US 141 is also a single-county affair.

[roadfro]

Similarly, you'll find a lot of Nevada state routes that do not cross county lines. Given the large size of many Nevada counties (larger than some whole New England states) this isn't overly surprising. It would take some time to compile a list...might be easier to list routes that *do* cross county lines...

[OracleUsr]

NC 610 in High Point (Guilford County) and NC 400 in Manteo (Dare County) come to mind right away

[DTComposer]

More California:

San Luis Obispo County
227
229

Santa Barbara County
135
154
192
217
225
246

Ventura County
34
232

Los Angeles County
19
27
47
107
134
187
213

Orange County
55
73
133
241
261

[oscar]

Every state highway in Hawaii is one-county.

Only a few of Alaska's dozen numbered state highways (1-11, and 98), leaving aside hundreds of routes with nothing more than unsigned inventory numbers: 

9 (Kenai Peninsula borough)

98 (Skagway borough)

5 (Southeast Fairbanks census area within the Unorganized Borough, which is the large part of Alaska not yet assigned to any county-level local government)

10 (Valdez-Cordova census area within the Unorganized Borough).

4 is entirely within the Unorganized Borough, but starts in the Valdez-Cordova census area and ends in the Southeast Fairbanks census area. 

[Darkchylde]

Louisiana has literally too many for me to think of and post.

[pianocello]

I-97.

Since the thread is about State Highways, I'll also include IN-520 and Iowa Highways 100, unsigned 461, 922, 965, and all of the other little spurs that were decommissioned in 2003.

[Eth]

Maryland has tons and tons of them.  I'm pretty sure I can come up with at least fifteen or twenty in Montgomery County alone.

[Scott5114]

Oklahoma has quite a few of them. Most of the lettered highways are short spurs to a town just off the main route, so those will tend to be in one county. Even the non-suffixed routes will sometimes be all in one county, though. Examples are OK 130 (McClain), OK 135 (unsigned, Tulsa), OK 145 (Garvin), OK 153 (Love), OK 209 (Choctaw, I think). There are even some lower numbered ones–OK 24 (McClain, although a few miles of the southbound/eastbound lane are in Garvin), OK 42 (Washita), OK 96 (Love).

[vdeane]

I can think of a zillion ones off the top of my head.  A couple notable ones:
-NY 421 is entirely in St. Lawrence county, but to reach it by car, you have to drive through Franklin county
-NY 272 is entirely in Monroe county northbound and Orleans county southbound.  It's possible to clinch this road without entering one of the counties it travels through.

[Big John]

Highway 30 is the only one I can think of off hand for Wisconsin.

More I can think of offhand:

WI 15
WI 24
WI 68
WI 74
WI 79
WI 105
WI 111
WI 117
WI 119
WI 122
WI 123
WI 124
WI 125
WI 126
WI 127
WI 129
WI 147
WI 152
WI 155
WI 157
WI 158
WI 159
WI 165
WI 172
WI 186
WI 193
WI 241 (southern terminus in question though)
WI 243
WI 310
WI 341 (unmarked)
WI 794
I-794
I-894

[jasonsk287]

We have a few of these on Long Island, NY also: NY State Routes 110, 111 and 112 and 114 are entirely in Suffolk County. Nassau County has 106, 107, 101, and probably some more that I'm forgetting. I guess the geography of Long Island plays a large role here. Many North/South routes are in one county because the counties cover from the North Shore to the South Shore.

[MVHighways]

Mass. Route 4 in Middlesex County.

This does not matter much in New England though, as many counties have no government--MA has 14 counties and 8 of them have no government--and there are ZERO county routes in the 6 states.

[Takumi]

Like other states, Virginia has many of these. Note that I'm counting independent cities as counties. This is maybe half of them.
VA 4
VA 9*
VA 26
VA 27
VA 32
VA 34
VA 38
VA 54/54Y
VA 59
VA 62*
VA 68?
VA 70*
VA 73
VA 78
VA 79
VA 82
VA 84*
VA 86*
VA 87*
VA 90
VA 93*
VA 96*
VA 98
VA 99
VA 101
VA 103*
VA 108
VA 111
VA 140
VA 185
VA 192
VA 196
VA 204
VA 226
Every route in the Eastern Shore except VA 178
Almost every 3xx number except 307, 309, 311, 337, 345, 360, and 361

NC 46*
NC 186*
NC 615
NC 902

*keeps number across state border

[jp the roadgeek]

Ok, I'll do Connecticut.  Numbers with an asterisk are highways that continue into another state (in the case of 138, 2 states)

Fairfield: 25, 33, 35*, 37, 39, 53, 55*, 57, 58, 59, 102, 104, 106, 107, 108, 110, 111, 113, 116*, 123*, 124, 127, 130, 135, 136, 137*, 302

New Haven: 22, 40, 42, 68, 70, 77, 100, 103, 114, 115, 121, 122, 139, 142, 146, 150, 152, 162, 172, 188, 243, 313, 334, 337

Hartford: 71A, 75*, 120, 159*, 160, 167, 168*, 173, 174, 175, 176, 177, 178, 185, 187*, 189*, 191, 192*, 194, 218, 220*, 229, 287, 305, 309, 314, 315, 364

Middlesex: 81, 145, 147, 151, 153, 154, 155, 157, 166, 196, 217

Tolland:19*, 31, 186*, 275, 286, 316, 319, 320

New London: 11 27, 78*, 117, 138*, 161, 163, 164, 165*, 184, 201, 213, 214, 215, 216*, 234, 349, 354

Also: I-684 skirts Fairfield County, I-291 is entirely within Hartford County, and one side of NY Route 120A is in Greenwich in Fairfield County.

[Alps]

NJ, off the top of my head (so pardon any errors):
5 - Bergen (original 5 followed 46 to Passaic, Essex, Morris)
13 - Ocean
17 - Bergen (multi-state route)
19 - Passaic (originally proposed as 20)
20 - Passaic (also in Bergen until 1988)
26 - Middlesex (followed 1 to Mercer until 1953)
32 - Middlesex
33 Business - Monmouth
36 - Monmouth
37 - Ocean (once proposed as freeway to Mercer)
48 - Salem (followed 40 to Atlantic until 1953)
53 - Morris
59 - Union
62 - Passaic
63 - Bergen
64 - Mercer
66 - Monmouth
67 - Bergen
68 - Burlington
75 (unbuilt) - Essex
I-76 - Camden
79 - Monmouth
82 - Union
83 - Cape May
87 - Atlantic (originally proposed with a bridge to Ocean)
88 - Ocean
91 - Middlesex
93 - Bergen
***
I-278 - Union
284 - Sussex
324 - Gloucester
439 - Union
445X (Brigantine Connector) - Atlantic
446, 446S (Palisades Parkway) - Bergen
495 (already mentioned) - Hudson

*** Most of the 1xx routes are in a single county. In fact, here are the ones in multiple counties: 124, US 130, 158 (former), 159, 167, 168, 173, 181, 183, I-195.

[roadman65]

FL 435 Orange
FL 482 Orange
FL 536 Orange
FL 408 Orange
FL 526 Orange
FL 551 Orange
FL 552 Orange
FL 423 Orange (exists also as CR 423 as well)
FL 416 Orange
FL 527 Orange
FL 437  Orange(now defunct)
FL 438 Orange (used to enter Lake County, now truncated to Oakland)

There are tons in Florida.  Too many to list, but these are primarily in Orange County.