Chain of State highways

[jwolfer]

FL-GA-SC 121 from Gainesville FL to Newberry SC..

[DandyDan]

Minnesota and Iowa have numerous "chained" state routes. State Highways 4, 15, 26, 60, 76, 86, 91, and 139 all maintain their numbers when crossing the border between the two. I'm only mentioning it for the high degree of coordination between the two states since I'm guessing you're more interested in examples of 3+ states (all of these chains only exist in MN/IA).

Iowa 91 was decommissioned in 2003, but other than that, it's all true.

Illinois to Iowa   IL 92/IA 92   IL 136/IA 136

Was going to mention route 92, so I'll add that it also carries westward into Nebraska as NE-92.

And then onward to Wyoming as WY 92.

A couple interesting ones in Nebraska besides Highway 92 is NE 2 and IA 2, only it's the eastern segment of NE 2, and then CO/NE/SD 71, the interesting thing about that being SD 71 fits a grid, while the others are just random numbers.

[CNGL-Leudimin]

While not a state highway chain, British Columbia numbered their provincial highways after U.S. routes and state highways at border crossings:

BC 97 & US 97 at Osoyoos, BC

This extends all the way to Yukon. If that territory renumbered YT 1 to YT 97, Alaska could have had US 97. But that didn't happen.

BC 93 & US 93 at Roosville, BC

Which then crosses into Alberta and, unlike Yukon and 97, they numbered their part as AB 93.

[ftballfan]

Only one I can think of in Michigan: M-49 -> OH 49
There USED to be IN 120 -> M-120 -> OH 120 until M-120 was decommissioned and its number reused on a portion of what used to be M-20

[GaryV]

MI/WI - M-26 used to connect with STH-26, until replaced by US-45.  This would be purely by coincidence, as both MI and WI numbered their original routes by decreasing length.

[NE2]

MI/WI - M-26 used to connect with STH-26, until replaced by US-45.  This would be purely by coincidence, as both MI and WI numbered their original routes by decreasing length.

It was probably done on purpose; WI 26 didn't originally make it to the state line: http://wisconsinhighways.org/listings/WiscHwys20-29.html#STH-026

[paulthemapguy]

Iowa and Missouri have matching 5's and 81's.

[Greybear]

Count Arkansas in on the 5's. AR/MO/IA 5 runs from just north of Jacksonville AR to Des Moines IA

[GaryV]

MI/WI - M-26 used to connect with STH-26, until replaced by US-45.  This would be purely by coincidence, as both MI and WI numbered their original routes by decreasing length.

It was probably done on purpose; WI 26 didn't originally make it to the state line: http://wisconsinhighways.org/listings/WiscHwys20-29.html#STH-026

Interesting - following the link, STH-15 and M-15 also connected; they were superseded by US-41.

[Scott5114]

OK/KS/NE 99. TX 99 used to connect to it as well.

[WNYroadgeek]

PA/NY/PA 426

[jmd41280]

PA/MD 97 begins at US 15 in Gettysburg, PA and ends at US 29 in Silver Spring, MD

PA/MD 194 begins at PA 74 near Dillsburg, PA and ends at MD 26 near Frederick, MD

NY/PA 14 begins at the Lake Ontario shore in Sodus Point, NY and ends at US 15 (future I-99) at Trout Run, PA

2 shorter examples:

MD/PA 669 begins at US 40-Alt in Grantsville, MD and ends at US 219 in Salisbury, PA

PA/WV 218 begins at US 19/PA 21 in Waynesburg, PA and ends at US 19 in Worthington, WV