Longest String of Sequential Route Numbers?

[Thing 342]

Found another set of 8:
FM-58
US-59 (Lufkin, TX)
US-60 (Afton, OK)
US-61 (Sikeston, MO)
US-62 (Howardville, MO)
US-63 (Hardy, AR)
US-64 (Marion, AR)
US-65 (Conway, AR)
AR-66 (Leslie, AR)

[Duke87]

Here's another set of 7:

I-79
I-80 (Mercer, PA)
US 81 (York, NE)
US 82 (Ringgold, TX)
US 83 (Guthrie, TX)
US 84 (Abeliene, TX)
US 85 (Santa Fe, NM)

I feel like there must be a set of 8 somewhere, but I'm not finding it.

...CO 86, US 87, CO 88

Mapmikey

I coulda sworn I looked and determined that CO 86 didn't exist. But then it was like 4 AM so who knows what I was thinking.

Anyways, this is a weird case since US 85, CO 86, and US 87 actually all meet at the same interchange. So, while you do in theory have a continuous set of sequentially numbered roads intersecting each other, it is not reasonable to drive from US 85 to CO 86 to US 87 unless you make a U-turn or use another road to double back.

Nonetheless, based on the original wording there's no reason not to count it (if we disallow U-turns we'd also have to disqualify the OP example based on missing ramps between US 5 and US 6), so that brings it up to a full sequence of 10, which at least in the US is probably a winner.

Anyone got a set of 11?

[NWI_Irish96]

Within Indiana, you can do US35-US36-IN37-IN38-IN39-US40-US41.

If you want to go outside the state to make the string longer, US35 interstects WV34, and on the other end, US41 instersects GA42

[Rover_0]

Utah:

Nowadays, exiting SB US-89/91 onto SR-90 (basically a spur into downtown Brigham City), flipping a U-turn, then returning onto NB 89/91. A little tricky, not very useful, but possible.

Historically, using the old hierarchical routing in its latest incarnation: I-15 (SR-1) to I-80 (SR-2) to I-80N LKA 84 (SR-3).