Which states have clusters of similar-numbered state roads close to one another?

[KCRoadFan]

The premise of this thread stems from something I observed when I was looking at the map of Illinois in the Rand McNally road atlas. I noticed that throughout many regions of the state, there appeared to be several state routes with similar numbers in close proximity, namely:

• Many numbers in the 50's, 60's, 70's, and 80's throughout the Chicago area
• 90's and 100's in western Illinois (Quincy, Macomb, Galesburg, etc.)
• 110's in the area of northeast Illinois outside of Chicagoland (Kankakee, etc.) 
• 120's and some 130's in central and east-central Illinois (Bloomington-Normal and Champaign-Urbana areas, etc.)
• Some other 130's, as well as 140's, 150's, and 160's, in southern Illinois (Metro East, "Little Egypt", Carbondale, etc.)

Aside from Illinois, I've also seen similar-numbered roads clustered together in Nevada, such as the many roads in the 580, 590, and 600 range in Vegas (in fact, I thought I read somewhere that Nevada actually assigns number ranges based on the county). As for other states, I know that in Mississippi, the first digit of 3-digit roads is based on the location within the state (300's in the north, 400's in the middle, 500's in the south, and 600's in the Gulf Coast area). Similarly, I've seen that in Florida, the first digit of 3-digit roads tends to increase the further south you go: you'll see 100, 200, and a few 300-series roads in the Panhandle; 400 and 500-series in Orlando; 500 and 600-series in Tampa-St. Pete; 700-series in Sarasota and WPB, and 800 and 900-series in the Miami area.

Besides the states I've mentioned above, in what other states have you observed a bunch of state highways with similar numbers clustered in close proximity?

[Takumi]

Virginia used to have its routes numbered strictly by districts. There's still plenty of evidence of that around now. The Richmond area has 142, 144, 145, 146, 147, and 150 (which was later), for example.

[ski-man]

Wyoming has most of it's state highway numbers clustered by county and similar number sequences.

[tdindy88]

Indiana has a grid system so this doesn't come up to much, but the Evansville area, including Posey, Gibson, Warrick and Vanderburgh Counties do feature several highways that are in the 60s. Hamilton County has four highways in the 30s but that's about it.

[webny99]

I'm not sure if there's any exact correlation in how New York State Routes are numbered, but it seems more than mere coincidence that 250, 251, 252 and 253 are all in the same area near Rochester, and 263, (but not 264), 265, and 266 are all in the same area near Buffalo.

You also have NY 12, NY 13, NY 14, NY 15, and NY 16 running along parallel corridors that line up quite nicely heading east to west across the state.

[oscar]

Hawaii clusters by island: 1xxx and 2xxx, Big Island; 3xxx Maui; 4xx (only three-digit secondary routes there) Lanai and Molokai; 5xxx Kauai; and 6xxx, 7xxx, 8xxx, and 9xxx Oahu.

[Hot Rod Hootenanny]

Much of Ohio

[vdeane]

I'm not sure if there's any exact correlation in how New York State Routes are numbered, but it seems more than mere coincidence that 250, 251, 252 and 253 are all in the same area near Rochester, and 263, (but not 264), 265, and 266 are all in the same area near Buffalo.

You also have NY 12, NY 13, NY 14, NY 15, and NY 16 running along parallel corridors that line up quite nicely heading east to west across the state.

It was indeed initially done that way in the great 1930s renumbering.  Low-numbered routes (2dny, more or less) followed the core long-distance corridors while higher-numbered routes (3dny) were clustered.  Since then, newer routes have been assigned without regard to clusters.  Many out of cluster numbers are evidence of various things, like NY 104 and NY 404 (former US 104) or NY 531 (parallel to NY 31).

[Ben114]

The nearest to me would be in north RI, with RI 94, 96, 98, 100, 102, and 104.

[STLmapboy]

Florida increases as you go south, with 900s in the Miami area.

[KCRoadFan]

Florida increases as you go south, with 900s in the Miami area.

As was mentioned in the OP.

[TheHighwayMan3561]

Minnesota has MN 56, 57, and 58 (along with the old MM 59, which was absorbed into US 63) in the same general region. It came later into the area, but all three of those also intersect MN 60, and a piece of MN 55 could be considered in this area's orbit as well.

[STLmapboy]

Florida increases as you go south, with 900s in the Miami area.

As was mentioned in the OP.

D'oh! Didn't see the damn paragraph.

[US 89]

You'll find quite a few clusters scattered around Utah. The original 1927 system was highly clustered by geography - route numbers in the teens were all in the southwest part of the state, 20s in west-central Utah, 30s in northern Utah, and 40s generally in eastern Utah. And as the state assigned more highways, similar numbers would usually be placed near each other - for example, the original SRs 103 through 110 were all east-west routes branching off US 91 in Weber and Davis County, with numbers increasing to the south.

Unfortunately, there hasn't really been much effort to preserve this in the last 50 years, so the system is much more random today. But a few obvious clusters do still exist - 268/269/270 in SLC and 118/119/120 in Richfield being prime examples - as vestiges of a more organized system in the past.

[formulanone]

Tennessee doesn't really have a grid, but a lot of three-digit routes tend to be sequentially grouped together.

[I-55]

A lot of 300-600s routes in MS are clustered, particularly near Memphis, Jackson, and the gulf.

Near Memphis, you can have 301, 302, 304, 304 Scenic, 305, 306, 309, and further out 310, 311, and 315.

Near Jackson you have 463, 467, 468, 469, 471, 475

Near the gulf you have 603, 604, 605, 607, 609, and a little further out 611, 613, 614, and the 619 bridge

I imagine clusters exist in plenty of other locations as well.

[Rover_0]

You'll find quite a few clusters scattered around Utah. The original 1927 system was highly clustered by geography - route numbers in the teens were all in the southwest part of the state, 20s in west-central Utah, 30s in northern Utah, and 40s generally in eastern Utah. And as the state assigned more highways, similar numbers would usually be placed near each other - for example, the original SRs 103 through 110 were all east-west routes branching off US 91 in Weber and Davis County, with numbers increasing to the south.

Unfortunately, there hasn't really been much effort to preserve this in the last 50 years, so the system is much more random today. But a few obvious clusters do still exist - 268/269/270 in SLC and 118/119/120 in Richfield being prime examples - as vestiges of a more organized system in the past.

Don't forget 7/8/9 all within ~30 minutes of each other around St. George.

[corco]

Idaho loosely clusters by number, though there are several exceptions -
0-10 Northern Idaho
11-20 Western Idaho
21-30 Central Idaho
31-40 Eastern Idaho
41-200 Not really clustered

Wyoming and Nevada both number their more minor state highways (Wyoming)/almost all their state highways (Nevada) alphabetically by county, which creates clusters.

[mrcmc888]

Tennessee doesn't really have a grid, but a lot of three-digit routes tend to be sequentially grouped together.

Occasionally, you will get two digit groupings as well, like TN-46/48/49 around Clarksville.

[-- US 175 --]

TX doesn't really do that with their state primary routes, but there are some loose clusters of secondary examples.  I don't think the RMs have this happen nearly as much as their FMs.

A couple of examples:
Between Tyler and Rusk, there is FM 343, FM 344, FM 346, and FM 347.
West of Lake Palestine and mostly in Henderson County, there is FM 314, FM 315, FM 316, and FM 317.

[cwf1701]

In Michigan, the Detroit Metro area and SE Michigan Has M-1, M-3, M-5, M-8, M-10, M-14, M-15, M-17, M-19, M-21, M-24, M-25, and M-29. Former routes in Metro Detroit include M-6 (1970s 11 Mile rd service Drive) and M-16 ( pre US-highways).

[DandyDan]

Minnesota has MN 56, 57, and 58 (along with the old MM 59, which was absorbed into US 63) in the same general region. It came later into the area, but all three of those also intersect MN 60, and a piece of MN 55 could be considered in this area's orbit as well.

The highways in the 200's that do not go to state facilities look like they are, or were, clustered. The 240's go from the Twin Cities area down to Caledonia. The 250's go from Lanesboro to the Blue Earth area. The 260's go to the SW corner. The 270's appear to be north of the 260's.

[sprjus4]

Virginia used to have its routes numbered strictly by districts. There's still plenty of evidence of that around now. The Richmond area has 142, 144, 145, 146, 147, and 150 (which was later), for example.

Hampton Roads has VA-162, VA-164 (coincidence, but acts as a 3di of I-64 and should be I-164), VA-165, VA-166, VA-168, VA-169, VA-170, VA-171, VA-172, and VA-173. Also, there's a small clusters in the 90s. VA-190, VA-191, VA-192, VA-194, and VA-199 (Williamsburg beltway).

The Eastern Shore has VA-175, VA-176, VA-178, VA-179, VA-180, VA-181, VA-182, VA-183, VA-184, and VA-187.

[cpzilliacus]

Maryland has clustered route numbers by county, with exceptions, as when a route crosses a county line. This goes back to the start of numbered state-maintained highways in the 1920's. Details can be found on the MDROADS site here.

[Takumi]

Virginia used to have its routes numbered strictly by districts. There's still plenty of evidence of that around now. The Richmond area has 142, 144, 145, 146, 147, and 150 (which was later), for example.

Hampton Roads has VA-162, VA-164 (coincidence, but acts as a 3di of I-64 and should be I-164), VA-165, VA-166, VA-168, VA-169, VA-170, VA-171, VA-172, and VA-173. Also, there's a small clusters in the 90s. VA-190, VA-191, VA-192, VA-194, and VA-199 (Williamsburg beltway).

The Eastern Shore has VA-175, VA-176, VA-178, VA-179, VA-180, VA-181, VA-182, VA-183, VA-184, and VA-187.

The missing numbers in those clusters also were in the area in decades past.