OK, which road passes through the most counties?

[Alps]

Discuss.

[agentsteel53]

OK, route 3 is my guess.

elsewhere?  no idea.

[Road Hog]

I'd guess SH 16 in Texas, since it's the longest state highway in Texas and Texas counties are relatively small.

OK 3 is probably up there as well and is even longer because it runs diagonally from the Panhandle all the way to the southeast corner (although most of it northwest of OKC is a duplex with US highways).

[Duke87]

If I counted correctly, I-90 passes through 100 counties exactly. Can any other transcontinental route beat that?

[Kacie Jane]

Just a guess, but I'd imagine that I-95 (which also passes through more states than I-90) would pass through more counties, as counties tend to be smaller on the east coast than they do in the rural west.

[vdeane]

If I counted right, I-95 only has 94.  Keep in mind that 95 passes thorough states that are much smaller than out west, and that states are rectangular as well, so a north-south route is guaranteed to pass through more than an east-west route of similar length in a similar part of the country.

[Kacie Jane]

I trust your count, but not your logic.  While there are a good number of states (probably most of them) that are rectangular horizontally -- that is, longer east to west -- there are also several that are longer north to south (California, Illinois, Indiana, Mississippi, Alabama, New Jersey, etc.) and several that are more or less square (Ohio, er... okay, so maybe not several).  I wouldn't say any such guarantee exists.

To be fair, my logic was not sound either.  While I would say counties are smaller in the east, the difference is not as dramatic as it is for states, so it makes sense that I-90 with its longer mileage would pass through more.

[Takumi]

Might the national answer be a US route? US 1, if I counted correctly, also has 94.

Virginia's is US 58, with 24. It was 27 before the Franklin Bypass was built in the early 1980s; the bypass removed it from Franklin and Isle of Wight County, and South Boston retroceded to Halifax County in 1995.

[hbelkins]

Are we talking within one state or in total (for US routes and interstates?)

[corco]

US 281, maybe?

[Kacie Jane]

Are we talking within one state or in total (for US routes and interstates?)

Why not both?  (Separate categories of course, but I'm interested in both answers.)

[Alps]

Are we talking within one state or in total (for US routes and interstates?)

Why not both?  (Separate categories of course, but I'm interested in both answers.)

I just threw it open, sort of as a parody of all the county threads springing up, to keep you guys occupied for a bit

[NE2]

Main Street. Hey, if AR 159 counts...

[ftballfan]

In Michigan
I-75 (15): Chippewa, Mackinac, Emmet, Cheboygan, Otsego, Crawford, Roscommon, Ogemaw, Arenac, Bay, Saginaw, Genesee, Oakland, Wayne, Monroe
US-31 (14): Cheboygan (barely), Emmet, Charlevoix, Antrim, Grand Traverse, Benzie, Manistee, Mason, Oceana, Muskegon, Ottawa, Allegan, Van Buren, Berrien
US-23 (13): Emmet (barely), Cheboygan, Presque Isle, Alpena, Alcona, Iosco, Arenac, Bay, Saginaw, Genesee, Livingston, Washtenaw, Monroe
US-131 (13): Emmet, Charlevoix, Antrim, Kalkaska, Grand Traverse, Wexford, Osceola, Mecosta, Montcalm, Kent, Allegan, Kalamazoo, St. Joseph
M-66 (13): Charlevoix, Antrim, Kalkaska, Missaukee, Osceola, Mecosta, Montcalm, Ionia, Eaton, Barry, Calhoun, Branch, St. Joseph

[vdeane]

I trust your count, but not your logic.  While there are a good number of states (probably most of them) that are rectangular horizontally -- that is, longer east to west -- there are also several that are longer north to south (California, Illinois, Indiana, Mississippi, Alabama, New Jersey, etc.) and several that are more or less square (Ohio, er... okay, so maybe not several).  I wouldn't say any such guarantee exists.

To be fair, my logic was not sound either.  While I would say counties are smaller in the east, the difference is not as dramatic as it is for states, so it makes sense that I-90 with its longer mileage would pass through more.

I think of those states more as outliers.

[roadman65]

In Florida US 98 is the longest route designation, so here in the Sunshine State it would have to pass through the most counties statewide.
Escambia
Santa Rosa
Okaloosa
Walton
Bay
Gulf
Franklin
Wakulla
Jefferson
Taylor
Dixie
Levy
Citrus
Pasco
Polk
Highlands
Okeechobee
Martin
Palm Beach

Counted 20 in all

US 1 the next longest continuous designation:
Monroe
Miami-Dade
Broward
Palm Beach
Martin
St. Lucie
Indian River
Brevard
Volusia
Flagler
St. Johns
Duval
Nassau
13 Counties in all

Need I say more about the Sunshine State
Although, US 90 does indeed enter all of the county seats of every county it passes through in Florida. 

Escambia- Pensacola
Santa Rosa- Milton
Okaloosa- Crestview
Walton- De Funiak Springs
Holmes- Bonifay
Washington- Chipley
Jackson- Marianna
Gadsen- Quincy
Leon- Tallahassee
Jefferson- Monticello
Madison- Madison
Suwanee- Live Oak
Columbia- Lake City
Baker- Macclemmy
Duval- Jacksonville

With these being noted it comes up to 15 (2 more than US 1 has) for a shorter route than the main East Coast Highway.  I guess you cannot go by distance as Kacie sort of implied.

[jp the roadgeek]

I counted 104 counties for US 6, if you count Madison County, Iowa (it forms the border between Adair and Madison County).

[bassoon1986]

In Louisiana:

I-10 (15)
US 90 (14)
US 190 and LA 1: (12)
US 167 (11)
LA 10: (10)
US 165, US 71, US 61,  and LA 2: (9)
I-20, I-49, US 80: (8)

[NWI_Irish96]

Within Indiana, I-65 covers 14 counties, and US 31 and US 231 each cover 13.  If you combine the two sections, IN 3 covers 15 counties.  When completed, I-69 will cover 17 counties.

[agentsteel53]

anyone got the numbers for US 6, 11, 20, and 41?