I stand to be corrected but I don't believe we've done this before.
Which route(s) enter the most counties in each state?
In NY, I believe I-90 wins with 16 (of 62) counties.
Also noteworthy:
US 20 - 15
US 9 - 12
I-87 - 11
I-86/NY 17 - 11
My first thought was I-10 across Texas. Eyeballing an on-line map of dubious accuracy, it looked like it hit 25 counties in the state.
California:
I-5 - 17
US-101 - 14
CA-1 - 12
CA-99 - 12
Maryland:
US 40 hits 10 of 24 counties/independent cities (40 is also, not-coincidentally, the longest signed route in MD)
Other honorable mentions:
US 50 - 8
US 1 - 6
I-95 - 6
US 301 - 6
I-70 - 6
For Michigan, it would be I-75 at 15 counties. Next up is US 31 at 14 and then US 23 and US 131 tied at 13 each.
For Utah, the big winner is US 89, which enters 12 of the 29 counties. Other notable mentions include I-15 (10) and US 6 and 191 (7).
There's also a category of routes that used to be significantly longer, but were shortened due to Interstate-related truncations or decommissionings. US 91 is the most notable member of that class - back in its day it entered 11 counties, but is now down to 2.
As for state routes: Utah doesn't have state route concurrencies for the most part, so routes generally aren't that long and it's quite rare for one to cross multiple county lines. The most counties served by a single state route is 4, on SR 24.
For Florida we have 20 for US 98. 16 for US 90. Though I mentioned it before in another thread, the latter enters 14 consecutive county seats along its journey from Alabama to SR A1A.
I-69 enters 19 counties in Indiana (will still be 19 once the last section is finished).
MN. US 59 (17)
Other routes people were probably curious about:
MN 23: 14 + 1 WI
US 75: 14
US 71: 13
I-35: 10/12/13 depending on your views on the W/E
I-94: 11
I-90: 9
I think that MA 9 enters 6 counties. MA 28 might also hit 6 too.
Quote from: dlsterner on June 16, 2020, 11:14:41 PM
My first thought was I-10 across Texas. Eyeballing an on-line map of dubious accuracy, it looked like it hit 25 counties in the state.
I think it's 26.
Quote from: US 89 on June 17, 2020, 01:06:46 AM
As for state routes: Utah doesn't have state route concurrencies for the most part, so routes generally aren't that long and it's quite rare for one to cross multiple county lines. The most counties served by a single state route is 4, on SR 24.
That's almost the polar opposite of New York, where there are many state routes that enter 4+ counties, largely because of the state's disdain for US routes.
One could say that I-278 is one of the few urban freeway interstates that enters 5 counties. As many are aware each borough of NYC is a separate county despite it having no county level government. However, they are still counties as I-278 in one municipality enters more counties than the State of Delaware has.
I don't think it's possible for a route to beat OK-3's 18 counties (the same no matter whether you use 3E or 3W).
Alabama
I-65 - 16
US31 - 15 (runs alongside I-65 but doesn't enter Mobile Co at the southern end)
US231 - 15
US431 - 12
US43 - 11
AL14 - 11
US80 - 10
AL5 - 10
AL17 - 9
AL21 - 9
Delaware: DE-1 and US-13 @ 3 :bigass:
Virginia: A rough count, but I believe that US-58 leads at 23 counties + independent cities. I-64 follows closely at 22.
Nevada:
I-80: 9
US 95: 8
US 50: 7 (Carson City counts as a county in these lists)
Special recognition to US 93 for entering just 4 counties despite its 524 miles within the state.
Louisiana:
I-10 at 15 parishes
US 90 just behind at 14
iPhone
For Ohio...
I-71 - 15
US 42 - 14
Oh 3 - 14
For Mississippi, it seems the Natchez Trace Parkway runs through 16 counties, edging out I-55's fifteen counties.
Quote from: kphoger on June 17, 2020, 12:51:38 PM
Quote from: dlsterner on June 16, 2020, 11:14:41 PM
My first thought was I-10 across Texas. Eyeballing an on-line map of dubious accuracy, it looked like it hit 25 counties in the state.
I think it's 26.
I-10 goes through 25 counties in Texas. Wikipedia lists 26, but that's because it includes Kerr County twice.
My first guess would be the state's longest road, US 83. It goes through 27 counties. This includes 1 minor corner, 1 very minor corner that would be easy to miss on a large map, and 1 very minor entry, about a tenth of a mile over the county line, that would also be easy to miss. The other one I think of is US 67, because it crosses diagonally and goes through east Texas, where counties are small. It goes through 26 counties.
In my state of Missouri:
Interstates:
I-44 goes through 12 counties and I-70 goes through 11 counties (that's if you count St. Louis City as a county, which I do).
US Routes:
US 60 and 61 both go through 15 counties; US 71 goes through 14 counties.
State Routes:
MO 5 (the only state route to connect to state lines at both ends) goes through 13 counties. MO 13, which goes from the Arkansas line up to Bethany (just 20 miles short of the Iowa line), goes through 12 counties.
For Arizona, the answer appears to be US 60, which enters 6 of Arizona's 15 counties.
Before US 89 was truncated at Flagstaff, it also entered six counties in Arizona.
If I-17 and I-19 were a single route, multiplexed with I-10 from Tucson to Phoenix, that route would also enter six counties.
Both I-10 and I-40 enter five Arizona counties.
Which highway enters the most counties nationally? I don't mean to hijack the thread, but it's a similar question and there's only one answer. Some of the northern highways are very long. Some of the eastern highways are long, and the counties tend to be smaller out that way. My guess is US 1.
I think we shouldn't count independent cities as counties, but we should count the county of which that independent city was once a part if the highway doesn't enter that county otherwise. Also, DC should be considered a county for this purpose.
In a previous thread, I stated US 6 is the leader for CT as it enter 6 of the 8 counties in the state (Middlesex and New London excluded). It goes Fairfield-New Haven-Litchfield-Hartford-Tolland-Windham-Tolland-Windham. I-84 and CT 66 are tied for 2nd at 5 each (Fairfield, New Haven, Hartford, Tolland, Windham [and Tolland again] for I-84; New Haven, Middlesex, Hartford, Tolland, Windham for CT 66).
Among Michigan state routes (if it re-enters a county it left, it's italicized):
M-66 - 13 (St. Joseph, Branch, Calhoun, Barry, Eaton, Ionia, Montcalm, Mecosta, Osceola, Missaukee, Kalkaska, Antrim, Charlevoix)
M-28 - 8 (Gogebic, Ontonagon, Houghton, Baraga, Marquette, Alger, Luce, Chippewa)
M-37 - 8 (Calhoun, Barry, Kent, Muskegon, Newaygo, Lake, Wexford, Grand Traverse)
M-46 - 7 (Muskegon, Kent, Montcalm, Gratiot, Saginaw, Tuscola, Sanilac)
M-50 - 7 (Kent, Ionia, Barry, Eaton, Jackson, Lenawee, Monroe) [prior to I-96's completion, it used to enter Ottawa County as well]
M-20 - 6 (Oceana, Newaygo, Mecosta, Isabella, Midland, Bay [barely])
M-33 - 6 (Arenac, Ogemaw, Oscoda, Montmorency, Presque Isle, Cheboygan)
M-43 - 6 (Van Buren, Kalamazoo, Allegan, Barry, Kalamazoo, Barry, Eaton, Ingham)
M-52 - 6 (Lenawee, Washtenaw, Jackson, Ingham, Shiawassee, Saginaw)
M-55 - 6 (Manistee, Wexford, Missaukee, Roscommon, Ogemaw, Iosco)
M-72 - 6 (Leelanau, Grand Traverse, Leelanau, Grand Traverse, Kalkaska, Crawford, Oscoda, Alcona)
M-21 used to enter eight counties (Ottawa, Kent, Ionia, Clinton, Shiawassee, Genesee, Lapeer, St. Clair) prior to the completion of I-196 and I-69.
M-78 used to enter nine counties (St. Joseph, Branch, Calhoun, Barry, Eaton, Ingham, Clinton, Shiawassee, Genesee) prior to the completion of I-69 and its truncation south of Battle Creek in favor of M-66 (it still enters three counties despite being a very short route).
M-37 very narrowly avoids a ninth county (Manistee).
M-115, which enters five counties (Benzie, Manistee, Wexford, Osceola, Clare), comes within a mile of both Missaukee and Isabella counties.