What's the longest US highway

[Voyager]

I was wondering what it is.

[TheStranger]

Presently, US 20; historically, US 6.

[Voyager]

Oh, thanks.

[ComputerGuy]

How about the longest north-south (historically and currently)?

[ComputerGuy]

How about in the "no longer existing category"?

[SSOWorld]

How about in the "no longer existing category"?

I think that category no longer exists *rimshot*

[ComputerGuy]

LOL master son, but seriously, I'd like to know the longest decomissioned north-south/south-north U.S. route.

[ComputerGuy]

66 and 99?

[Duke87]

Anticipating a possible future question:

281 is the longest 3 digit US route.

[ComputerGuy]

Hmm...how about the longest decomissioned 3-digit route?

[ComputerGuy]

Thanks for the links...my questions are answered.

[Duke87]

Hmm...how about the longest decomissioned 3-digit route?

Looks like 666 is the winner.

[ComputerGuy]

He he...now its 191 and 491.

[Tom]

Presently, US 20; historically, US 6.

Since there's a gap in US-20 in Yellowstone Park, US-6 is still the longest continuous route.

[Quillz]

US-1 is the longest north-south U.S. highway.

[ctsignguy]

OK, now how about the longest diagonal US highway (NE-SW or SE to NW)? 

US 52  NW-SE 
US 62  SW to NE?

Or did i forget one?

[mightyace]

Does US 11 count as a diagonal?

New Orleans (SW) to Rouses Point, NY (NE)

I does spend significant parts of its route going east-west including through my hometown of Bloomsburg, PA.

[SEWIGuy]

Current:

US-20 is the longest if you count both sections:  3237 mi.
US-6 is the longest continuous:  3205 mi.
US-1 is the longest north/south: 2376 mi.
US-281 is the longest 3dus: 1872 mi.
US-160 is the longest e/w 3dus: 1465 mi.

Historic:

US-6: 3652 mi.
US-1 (n/s): 2390 mi.
US-281...unless you count US-101: 1896 mi.

[Quillz]

US-101 is officially a 2dus... 10-1.

[thenetwork]

Current:

US-6 is the longest continuous:  3205 mi.

According to C-DOT, US-6 now ends in Mack, CO -- 12 miles from the UT Border, but we all know better.  Last week, I saw the "END 6" sign they must have put up sometime in the last year -- I have yet to see it on any street-view website.  I'll be back out there next week, with camera in hand for proof.

But then again C-DOT has pretty much abused US-6 for years. This is just another layer of icing on the cake.

[Michael in Philly]

Presently, US 20; historically, US 6.

Since there's a gap in US-20 in Yellowstone Park, US-6 is still the longest continuous route.

I'd have guessed US 30.