Longest distance you can travel with only an interstate or US route's family

[SkyPesos]

Rules:
- A family of highways include a 2-digit interstate or US route, and all of its 3-digit routes, suffixed routes, bannered routes, etc.
- You're not allowed to use an already traveled segment in either direction.
- You're not allowed to use any routes not part of the family at all. This means you can't use I-275 to get between I-71 and I-471, as an example.
- State routes that are related to an interstate or US route aren't allowed either. For example, you can't use CO 470 or MO 370 as part of an I-70 family routing.
- There will be two versions. An easy mode that includes only the 2-digit parent, its 3-digit routes and directional suffixed routes, and a hard mode that includes all of the above as well as bannered routes (alternative, business, etc).

I'll use I-75 in easy mode as an example.
- I-75 route length by itself is 1786 miles
- I-275 Tampa is 60 miles, compared to 46 miles staying on I-75: +14 miles
- I-275 Cincinnati entire loop: +84 miles
- I-475 Toledo: +8 miles
- I-475 Flint: +3 miles
- I-675 Saginaw: +2 miles

Total on the I-75 family without bannered routes: 1897 miles.

[Hobart]

Using US-95, US-95 Alternate in Nevada, US-195 and its spur, and US-395, its possible to travel 2,661 miles.

I have no idea how to make one word the link. Here it is, though.

EDITS: corrected a couple errors, this should be good
https://www.google.com/maps/dir/32.4869305,-114.7822573/46.4812442,-117.0378989/47.6395394,-117.4678554/34.3979911,-117.4029945/@37.3027517,-119.919431,6z/data=!4m56!4m55!1m35!3m4!1m2!1d-114.6948633!2d32.5967553!3s0x80d659ee0ebf59d9:0xa998daca12c6b6a6!3m4!1m2!1d-114.6504331!2d32.6951909!3s0x80d6f63bea840571:0xb32b7f8e2fb4a4f2!3m4!1m2!1d-114.4177284!2d33.6291433!3s0x80d1443b19b7ded7:0xdc2e38ff4a6aaa3f!3m4!1m2!1d-117.537464!2d38.1330169!3s0x80bc160bb510a279:0x2490a4a58aa61d76!3m4!1m2!1d-119.2245866!2d39.4374453!3s0x8098f07ba143c3b7:0x36856aeb650bbe2d!3m4!1m2!1d-117.0642943!2d43.0877749!3s0x54b1ee80376b2185:0x86221f8fe97c64b4!3m4!1m2!1d-116.9250448!2d44.2891805!3s0x54a582822f3689f3:0xa6d9d1888a3729fc!1m0!1m15!3m4!1m2!1d-119.2901294!2d45.8595487!3s0x54a2b94412db2661:0x2d57a8cd515a17de!3m4!1m2!1d-120.5165031!2d40.3759035!3s0x809dc0b33f0a5adb:0x829212cf59d2d149!3m4!1m2!1d-118.3969977!2d37.3754298!3s0x80be1608c40f3fb7:0xd70966aafe05619e!1m0!3e0

The funny thing is that there's all of this madness to get between two points that are only 287 miles apart.
https://www.google.com/maps/dir/34.3980111,-117.4029299/32.4869687,-114.7822366/@32.4866003,-114.7824855,18.08z/data=!4m2!4m1!3e0

It's also funny to me that a highway as short as US 195 has a spur that's as long as its parent.

[Techknow]

For Interstate 80, I'm going to assume based on the 3rd rule it is not allowed to get off an interstate, traverse some streets, then get on another interstate.

This means it is not okay to travel on I-280 north in San Francisco, get off at the Sixth Street exit where the freeway ends because it doesn't connect to I-80 (only via I-680/I-880), and drive 1/4 of an mile to get back on I-80 East.

So...

Start at I-280 South in San Francisco from King Street
Transfer to I-680 North at its south terminus - 57 miles
Transfer to I-580 West - 30 miles
I-580 West has a concurrency with I-80 East at Oakland - 25 miles
Continue on I-80 East all the way to I-95 East or I-280 in New Jersey then I-95 East - ~2893 miles to go straight to I-95

Which is... roughly 3005 miles

[SkyPesos]

For Interstate 80, I'm going to assume based on the 3rd rule it is not allowed to get off an interstate, traverse some streets, then get on another interstate.

This means it is not okay to travel on I-280 north in San Francisco, get off at the Sixth Street exit where the freeway ends because it doesn't connect to I-80 (only via I-680/I-880), and drive 1/4 of an mile to get back on I-80 East.

So...

Start at I-280 South in San Francisco from King Street
Transfer to I-680 North at its south terminus - 57 miles
Transfer to I-580 West - 30 miles
I-580 West has a concurrency with I-80 East at Oakland - 25 miles
Continue on I-80 East all the way to I-95 East or I-280 in New Jersey then I-95 East - ~2893 miles to go straight to I-95

Which is... roughly 3005 miles

A few more minor details about I-80:
- I-280 in the Quad Cities adds about a mile.
- Using I-480 in Cleveland adds about 8 miles
- In the past, you could use I-680 in Omaha to get +6 miles, but that is no longer an option as I-680 got truncated in the east and concurrency with I-29 no longer exists to connect with what is now I-880.

[Mapmikey]

For Interstate 80, I'm going to assume based on the 3rd rule it is not allowed to get off an interstate, traverse some streets, then get on another interstate.

This means it is not okay to travel on I-280 north in San Francisco, get off at the Sixth Street exit where the freeway ends because it doesn't connect to I-80 (only via I-680/I-880), and drive 1/4 of an mile to get back on I-80 East.

So...

Start at I-280 South in San Francisco from King Street
Transfer to I-680 North at its south terminus - 57 miles
Transfer to I-580 West - 30 miles
I-580 West has a concurrency with I-80 East at Oakland - 25 miles
Continue on I-80 East all the way to I-95 East or I-280 in New Jersey then I-95 East - ~2893 miles to go straight to I-95

Which is... roughly 3005 miles

A few more minor details about I-80:
- I-280 in the Quad Cities adds about a mile.
- Using I-480 in Cleveland adds about 8 miles
- In the past, you could use I-680 in Omaha to get +6 miles, but that is no longer an option as I-680 got truncated in the east and concurrency with I-29 no longer exists to connect with what is now I-880.

You can get 3051 miles doing this:
https://www.google.com/maps/dir/New+York+City,+NY/38.2148357,-122.1380204/37.6993371,-121.9308558/37.8074674,-122.2393889/37.8062779,-122.2784793/37.3171992,-121.9396778/37.3809968,-121.8590734/37.7015408,-121.9022087/37.5928263,-121.3363866/@41.2604493,-113.6932568,4271194m/data=!3m1!1e3!4m21!4m20!1m10!1m1!1s0x89c24fa5d33f083b:0xc80b8f06e177fe62!2m2!1d-74.0059728!2d40.7127753!3m4!1m2!1d-81.7104622!2d41.4215013!3s0x8830ef75f19eb7e9:0x7dd68b6119dd0aa!1m0!1m0!1m0!1m0!1m0!1m0!1m0!1m0!3e0

[Great Lakes Roads]

Correct me if I am wrong, but I got a total distance of 3,118 miles on I-90 and some of its family.

(I-290 in Chicago, I-190 to I-290 in Buffalo, I-490 to I-390 to I-590 back to I-490 in Rochester, and I-890 in Schenectady)

[SEWIGuy]

US-20 (if that counts as continuous) and US-6 are longer than any interstate combination come up with yet.

[SkyPesos]

US-20 (if that counts as continuous) and US-6 are longer than any interstate combination come up with yet.

Sorry if my title is a bit misleading, I meant the longest for each 2di or 2dus's family of routes, not the longest overall. Otherwise this thread will end pretty quickly.

[hotdogPi]

US-20 (if that counts as continuous) and US-6 are longer than any interstate combination come up with yet.

Sorry if my title is a bit misleading, I meant the longest for each 2di or 2dus's family of routes, not the longest overall. Otherwise this thread will end pretty quickly.

I don't think it would end that quickly; sometimes you can double back. For example, US 2 and US 202 meet at a location where you can make an acute angle. It won't win, though, as US 2 has a gap.

[Crown Victoria]

Interstate 95:

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations. And speaking of beltways, technically the Baltimore Beltway is not I-695 from I-97 east and north to I-95, so that will not be included in my calculation. A similar circumstance arises with the NJ Turnpike spurs, as the Eastern Spur is I-95, so that was used for this exercise.

So, here goes, using the "easy" way:

-Start at the southern terminus of I-95 in Miami, heading north to the southern I-295 junction in Jacksonville. 333 miles.
-Take I-295 completely around, then get back on I-95 north to go through downtown Jacksonville and onwards. 61 miles.
-I-95 from the southern I-295 (FL) junction north to I-295 (VA) near Petersburg. 584 miles.
-I-295 (VA) around Petersburg and Richmond to I-95 north of Richmond, then I-95 to the Springfield interchange. 129 miles.
-I-395 (VA) from the Springfield Interchange to I-695 (DC) to I-295 (DC-MD) to inner I-495 Capital Beltway back to the Springfield Interchange. 27 miles
-I-495 inner Beltway to I-95 College Park interchange, then I-95 to the southern I-695 Baltimore Beltway interchange. 53 miles.
-I-695 Baltimore Beltway between the I-95 interchanges. 27 miles.
-I-95 from the northern I-695 Baltimore Beltway interchange to the PA Turnpike interchange, using I-495 (DE). 109 miles.
-I-295 (PA-NJ) from the PA Turnpike interchange to I-195 (NJ) to I-95 (NJ Turnpike). 36 miles.
-I-95 from I-195 (NJ) to I-295 (RI-MA) to Attleboro, then south on I-95 to I-195 (RI-MA). 264 miles.
-I-195 (RI-MA) to I-495 (MA) to I-95 north of Boston. 165 miles.
-I-95 from I-495 (MA) to the Canadian border, using I-295 (ME) and the I-495 (ME) Falmouth Spur back to I-95. 328 miles.

Total mileage: 2,116.

*Total mileage will increase once I-295 (NC) is completed.

[MATraveler128]

Interstate 95:

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations. And speaking of beltways, technically the Baltimore Beltway is not I-695 from I-97 east and north to I-95, so that will not be included in my calculation. A similar circumstance arises with the NJ Turnpike spurs, as the Eastern Spur is I-95, so that was used for this exercise.

So, here goes, using the "easy" way:

-Start at the southern terminus of I-95 in Miami, heading north to the southern I-295 junction in Jacksonville. 333 miles.
-Take I-295 completely around, then get back on I-95 north to go through downtown Jacksonville and onwards. 61 miles.
-I-95 from the southern I-295 (FL) junction north to I-295 (VA) near Petersburg. 584 miles.
-I-295 (VA) around Petersburg and Richmond to I-95 north of Richmond, then I-95 to the Springfield interchange. 129 miles.
-I-395 (VA) from the Springfield Interchange to I-695 (DC) to I-295 (DC-MD) to inner I-495 Capital Beltway back to the Springfield Interchange. 27 miles
-I-495 inner Beltway to I-95 College Park interchange, then I-95 to the southern I-695 Baltimore Beltway interchange. 53 miles.
-I-695 Baltimore Beltway between the I-95 interchanges. 27 miles.
-I-95 from the northern I-695 Baltimore Beltway interchange to the PA Turnpike interchange, using I-495 (DE). 109 miles.
-I-295 (PA-NJ) from the PA Turnpike interchange to I-195 (NJ) to I-95 (NJ Turnpike). 36 miles.
-I-95 from I-195 (NJ) to I-295 (RI-MA) to Attleboro, then south on I-95 to I-195 (RI-MA). 264 miles.
-I-195 (RI-MA) to I-495 (MA) to I-95 north of Boston. 165 miles.
-I-95 from I-495 (MA) to the Canadian border, using I-295 (ME) and the I-495 (ME) Falmouth Spur back to I-95. 328 miles.

Total mileage: 2,116.

*Total mileage will increase once I-295 (NC) is completed.

I was going to do that one, but looks like you beat me to it.

[kirbykart]

Interstate 95:

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations. And speaking of beltways, technically the Baltimore Beltway is not I-695 from I-97 east and north to I-95, so that will not be included in my calculation. A similar circumstance arises with the NJ Turnpike spurs, as the Eastern Spur is I-95, so that was used for this exercise.

So, here goes, using the "easy" way:

-Start at the southern terminus of I-95 in Miami, heading north to the southern I-295 junction in Jacksonville. 333 miles.
-Take I-295 completely around, then get back on I-95 north to go through downtown Jacksonville and onwards. 61 miles.
-I-95 from the southern I-295 (FL) junction north to I-295 (VA) near Petersburg. 584 miles.
-I-295 (VA) around Petersburg and Richmond to I-95 north of Richmond, then I-95 to the Springfield interchange. 129 miles.
-I-395 (VA) from the Springfield Interchange to I-695 (DC) to I-295 (DC-MD) to inner I-495 Capital Beltway back to the Springfield Interchange. 27 miles
-I-495 inner Beltway to I-95 College Park interchange, then I-95 to the southern I-695 Baltimore Beltway interchange. 53 miles.
-I-695 Baltimore Beltway between the I-95 interchanges. 27 miles.
-I-95 from the northern I-695 Baltimore Beltway interchange to the PA Turnpike interchange, using I-495 (DE). 109 miles.
-I-295 (PA-NJ) from the PA Turnpike interchange to I-195 (NJ) to I-95 (NJ Turnpike). 36 miles.
-I-95 from I-195 (NJ) to I-295 (RI-MA) to Attleboro, then south on I-95 to I-195 (RI-MA). 264 miles.
-I-195 (RI-MA) to I-495 (MA) to I-95 north of Boston. 165 miles.
-I-95 from I-495 (MA) to the Canadian border, using I-295 (ME) and the I-495 (ME) Falmouth Spur back to I-95. 328 miles.

Total mileage: 2,116.

*Total mileage will increase once I-295 (NC) is completed.

Do you think the OP will allow unsigned interstates? I-495(ME) is unsigned.

[MATraveler128]

I'll try US 1, the major north south US highway on the east coast.

Starting in Key West, Florida, you get 869 miles from there to US 601 in Lugoff, SC. From Lugoff, SC to Bamberg, SC is 78 miles (Jct US 301). From there it is 151 miles to Rowland, NC where US 501 splits off. Then, follow US 501 for 47 miles up to US 1. From there it is 1,376 miles to the Canadian Border at Fort Kent, ME. This gives you a total of 2,521 miles unless someone can find a longer route.

[SkyPesos]

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations.

Yep, that's allowed. I did it with I-275 in the op example.

[Mapmikey]

I'll try US 1, the major north south US highway on the east coast.

Starting in Key West, Florida, you get 869 miles from there to US 601 in Lugoff, SC. From Lugoff, SC to Bamberg, SC is 78 miles (Jct US 301). From there it is 151 miles to Rowland, NC where US 501 splits off. Then, follow US 501 for 47 miles up to US 1. From there it is 1,376 miles to the Canadian Border at Fort Kent, ME. This gives you a total of 2,521 miles unless someone can find a longer route.

US 1 Key West to Lugoff SC - 869 miles
US 601 Lugoff to Orangeburg - 58 miles
US 301 Orangeburg to Latta - 118 miles
US 501 Latta to Conway - 45 miles
US 701 Conway to below Smithfield NC - 136 miles
US 301 Smithfield to Rowland - 91 miles
US 501 Rowland to Laurinburg - 23 miles
US 401 Laurinburg to Norlina - 163 miles
US 1 Norlina to Fort Kent ME - 1246 miles

2,749 miles.

I can't tell if you are using some longer US 1 ALT alignments in Maine, but that might add 30-40 more miles to it.

Another idea...let's see.

US 1 Key West to Raleigh NC (with US 501 detour to Carthage) - 1053 miles
US 401 Raleigh to Laurinburg - 103 miles
US 501 Laurinburg to Conway SC - 84 miles
US 701 Conway to below Smithfield NC - 136 miles
US 301 Smithfield to Petersburg VA - 155 miles
US 1 Petersburg to Fort Kent ME - 1167 miles

total - 2,698 so not as long

[Crown Victoria]

Interstate 95:

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations. And speaking of beltways, technically the Baltimore Beltway is not I-695 from I-97 east and north to I-95, so that will not be included in my calculation. A similar circumstance arises with the NJ Turnpike spurs, as the Eastern Spur is I-95, so that was used for this exercise.

So, here goes, using the "easy" way:

-Start at the southern terminus of I-95 in Miami, heading north to the southern I-295 junction in Jacksonville. 333 miles.
-Take I-295 completely around, then get back on I-95 north to go through downtown Jacksonville and onwards. 61 miles.
-I-95 from the southern I-295 (FL) junction north to I-295 (VA) near Petersburg. 584 miles.
-I-295 (VA) around Petersburg and Richmond to I-95 north of Richmond, then I-95 to the Springfield interchange. 129 miles.
-I-395 (VA) from the Springfield Interchange to I-695 (DC) to I-295 (DC-MD) to inner I-495 Capital Beltway back to the Springfield Interchange. 27 miles
-I-495 inner Beltway to I-95 College Park interchange, then I-95 to the southern I-695 Baltimore Beltway interchange. 53 miles.
-I-695 Baltimore Beltway between the I-95 interchanges. 27 miles.
-I-95 from the northern I-695 Baltimore Beltway interchange to the PA Turnpike interchange, using I-495 (DE). 109 miles.
-I-295 (PA-NJ) from the PA Turnpike interchange to I-195 (NJ) to I-95 (NJ Turnpike). 36 miles.
-I-95 from I-195 (NJ) to I-295 (RI-MA) to Attleboro, then south on I-95 to I-195 (RI-MA). 264 miles.
-I-195 (RI-MA) to I-495 (MA) to I-95 north of Boston. 165 miles.
-I-95 from I-495 (MA) to the Canadian border, using I-295 (ME) and the I-495 (ME) Falmouth Spur back to I-95. 328 miles.

Total mileage: 2,116.

*Total mileage will increase once I-295 (NC) is completed.

Do you think the OP will allow unsigned interstates? I-495(ME) is unsigned.

I don't see why not. Maine's I-495 is still an Interstate, even without the sign.

-A few items first. I did not see anything about crossing over/under a previously traveled route, so I will include a full circle of a beltway in my calculations.

Yep, that's allowed. I did it with I-275 in the op example.

Yeah I guess I should have noticed that. Thank you!

[Dirt Roads]

US-60 Brenda AZ -to- Norfolk VA (2,648)
US-460 Norfolk VA -to- Frankfort KY (655) <total 3,303 miles>

US-160 Tuba City AZ -to- Springfield MO (1,465)
US-60 Springfield MO -to- Norfolk VA (1,204)
US-460 Norfolk VA -to- Frankfort KY (655) <total 3,324 miles>

[Dirt Roads]

US-50 West Sacremento CA -to- Pruntytown WV (2,673)
US-250 Pruntytown WV -to- Sandusky OH (254) <total 2,972 miles>

Which, by the way, is less mileage than the parent route US-50 by itself <3,017>.   

[Dirt Roads]

US-30  Astoria OR -to- Camden NJ (3,018)
US-130  Camden NJ -to- Trenton NJ (53) <total 3,071 miles>  just slightly shorter than the parent US-30 distance

US-730  Walla Walla WA -to- Morrow OR (42)
US-30  Morrow OR -to- Camden NJ (2,752)
US-130  Camden NJ -to- Trenton NJ (53) <total 2,847 miles>  quite a bit shorter than the parent US-30 distance

[Crown Victoria]

US 19:

-Begin at the southern terminus at US 41 south of St. Petersburg, FL, proceeding north all the way to Weston, WV, using US 19E in NC and TN. 1108 miles.
-At Weston, WV, take US 119 north to DuBois, PA. 218 miles.
-Take US 219 south to US 460 at Rich Creek, VA. 375 miles.

Total: 1701 miles. US 219's southern terminus is only 20 miles from US 19 using US 460.

[NWI_Irish96]

OK, I think I got this right:

US 131 from Middlebury, IN at I-80/90 to Petoskey, MI at US 31 - 270 miles
US 31 from Petoskey, MI at US 131 to Louisville, KY at US 31E/31W - 597 miles
US 31W from Louisville, KY at US 31 to Nashville, TN at US 431 - 183 miles
US 431 from Nashville, TN at US 31W to Fayetteville, TN at US 231 - 86 miles
US 231 from Fayetteville, TN at US 431 to Crown Point, IN at US 41 - 507 miles

Total of 1643 miles, or 27% longer than the length of mainline US 31/31W.

[SkyPesos]

I-76 between I-71 and I-376 - 92 miles
I-376 between both I-76 interchanges - 59 miles
I-76 between I-376 and I-476 - 276 miles
I-476 NB between I-76 and I-81 - 115 miles

Total: 542 miles, 25% longer than the length of I-76 itself (434 mi)

[Crown Victoria]

US 85 and family:

-Start on US 85 at the Canadian border in Fortuna, ND and head south to US 385 at Deadwood, SD. 383 miles.
-Head south on US 385 to US 285 at Fort Stockton, TX. 1109 miles.
-Head north on US 285 to US 85 near Denver, CO. 771 miles.
-Head north on US 85 to US 385 at Deadwood, SD. 385 miles.

Total: 2648 miles. 

[JayhawkCO]

Interestingly for I-35, the longest way is direct with only the I-435 in KC loop added on. You just have to take I-35W in Minneapolis and I-35E in Dallas.

[Mapmikey]

US 21 and kin...


US 221 Perry FL to Blowing Rock NC - 519 miles
US 321 Blowing Rock to Columbia SC - 172 miles
US 21 Columbia to US 421 - 160 miles
US 421 US 21 to Michigan City IN - 688 miles

Total - 1539 miles