How many states are directly connected to yours via an interstate or US highway?

[KCRoadFan]

Here's an interesting game I thought up recently.

Think of the interstates and US highways that go through your state. Using those highways, how many states are directly connected to yours - that is, how many states are served by the interstates and US routes that go through your state? (In other words: if you were to get on an interstate or US highway somewhere in your state and drive in either direction, how many states could you reach by "following the number" without subsequently turning off the route?) What are some of the most- and least-connected states in that regard?

Obviously, Hawaii has no such connections; Alaska only connects to three states, if you count the Alaska Highway as being an extension of US 97 via BC 97.

Anyway, to start things off, here's a list of states that my state of Missouri is directly connected to via interstates or US highways. (In the following list, the first mention of a state will appear in boldface.)

I-29: IA, SD, ND
I-35: TX, OK, KS, IA, MN
I-44: TX, OK
I-55: LA, MS, TN, AR, IL
I-64: IL, IN, KY, WV, VA
I-70: UT, CO, KS, IL, IN, OH, WV, PA, MD
I-155: TN
I-255: IL
I-270: IL
I-435: KS
I-635: KS
I-670: KS
US 24: CO, KS, IL, IN, OH, MI
US 36: CO, KS, IL, IN, OH
US 40: UT, CO, KS, IL, IN, OH, WV, PA, MD, DE, NJ
US 50: CA, NV, UT, CO, KS, IL, IN, OH, WV, VA, DC, MD
US 54: TX, NM, OK, KS, IL
US 56: NM, OK, KS
US 59: TX, OK, KS, IA, MN
US 60: AZ, NM, TX, OK, IL, KY, WV, VA
US 61: LA, MS, TN, AR, IA, MN
US 62: TX, NM, OK, AR, IL, KY, OH, PA, NY
US 63: LA, AR, IA, MN, WI
US 65: LA, AR, IA, MN
US 67: TX, AR, IL, IA
US 69: TX, OK, KS, IA, MN
US 71: LA, AR, IA, MN
US 136: NE, IA, IL, IN
US 159: KS, NE
US 160: AZ, NM, CO, KS
US 169: OK, KS, IA, MN
US 275: IA, NE
US 400: CO, KS
US 412: NM, OK, TN

Based on the above list, we can see that Missouri is directly connected to 31 states (as well as DC) by interstate or US highways! How do other states measure up?

[SkyPesos]

Think there were maps a couple of months ago of something similar to this, but with number of counties instead of states. Illinois came out on top of the county maps.

But I'll play along with Ohio (duplicates not listed):

I-90: WA, ID, MT, WY, SD, MN, WI, IL, IN, PA, NY, MA (12)
I-80: CA, NV, UT, NE, IA, NJ (18)
I-77: SC, NC, VA, WV (22)
I-75: FL, GA, TN, KY, MI (27)
I-70: CO, KS, MO, MD (31)
US 6: CT, RI (33)
US 20: OR (34)
US 40: DE (35)
US 50: DC (36)
US 52: ND (37)
US 62: TX, NM, OK, AR (41, 40 without DC)

States missing (excluding AK and HI): AL, AZ, LA, ME, MS, NH, VT


EDIT: Decided to try Illinois too to see if it's the winner of the states in addition to the counties:

I-94: MT, ND, MN, WI, IN, MI (6)
I-90: WA, ID, WY, SD, OH, PA, NY, MA (14)
I-80: CA, NV, UT, NE, IA, NJ (20)
I-70: CO, KS, MO, WV, MD (25)
I-64: KY, VA (27)
I-55: LA, MS, TN, AR (31)
I-24: GA (32)
US 6: CT, RI (34)
US 20: OR (35)
US 40: DE (36)
US 41: FL (37)
US 45: AL (38)
US 50: DC (39)
US 52: NC, SC (41)
US 60: AZ, NM, TX, OK (45, 44 without DC)

States missing (excluding AK and HI): ME, NH, VT

[Great Lakes Roads]

I-64: MO, IL, KY, WV, VA
I-65: AL, TN, KY
I-69: MI, **KY, TN, MS, AR, LA, TX**
I-70: UT, CO, KS, MO, IL, OH, WV, PA, MD
I-74: IA, IL, OH
I-80: CA, NV, UT, WY, NE, IA, IL, OH, PA, NJ
I-90: WA, ID, MT, WY, SD, MN, WI, IL, OH, PA, NY, MA
I-94: MT, ND, MN, WI, IL, MI
I-265: KY
I-275: OH, KY
US 6: CA, NV, UT, CO, NE, IA, IL, OH, PA, NY, CT, RI, MA
US 12: WA, ID, MT, ND, SD, MN, WI, IL, MI
US 20: OR, ID, MT, WY, NE, IA, IL, OH, PA, NY, MA
US 24: CO, KS, MO, IL, OH, MI
US 27: FL, GA,, TN, KY, OH
US 30: OR, ID, WY, NE, IA, IL, OH, WV, PA, NJ
US 31: AL, TN, KY, MI
US 33: OH, WV, VA
US 35: WV, OH
US 36: CO, KS, MO, IL, OH
US 40: UT, CO, KS, MO, IL, OH, WV, PA, MD, DE, NJ
US 41: FL, GA, TN, KY, IL, WI, MI
US 50: CA, NV, UT, CO, KS, MO, IL, OH, WV, VA, DC, MD
US 52: SC, NC, VA, WV, KY, OH, IL, IA, MN, ND
US 131: MI
US 136: IL
US 150: IL, KY
US 224: OH, PA
US 231: FL, AL, TN, KY
US 421: NC, TN, VA, KY

Indiana is connected to 37 states and DC via interstates and US highways.

**Interstate 69 (if fully completed) would get another 4 new states: MS, AR, LA, TX, for a total of 41 states and DC.**

[sprjus4]

For Virginia interstates....

I-64 - WV, KY, IN, IL, MO
I-77 - SC, NC, WV, OH
I-81 - TN, WV, MD, PA, NY
I-85 - NC, SC, GA, AL
I-95 - FL, GA, SC, NC, MD, DE, PA, NJ, NY, CT, RI, MA, NE, ME
I-495 - MD

22 states via the interstate highway system. I-395 and I-66 also connect to DC, along with I-95.

In the future, we may see I-73 connect to NC and SC, I-785 connect to NC, and I-87 connect to NC.

[bassoon1986]

Louisiana doesn't get very far. 13 other states with our interstates.


iPhone

[Crown Victoria]

Pennsylvania's list, duplicates not included:

I-70: UT, CO, KS, MO, IL, IN, OH, WV, MD (9)
I-76: NJ (1)
I-78: NY (1)
I-79: No new states added
I-80: CA, NV, WY, NE, IA (5)
I-81: TN, VA (2)
I-83: No new states added
I-84: CT, MA (2)
I-86: No new states added
I-90: WA, ID, MT, SD, MN, WI (6)
I-95: FL, GA, SC, NC, DC, DE, RI, NH, ME (8 plus DC)
I-99: No new states added
US 1: No new states added
US 6: No new states added
US 11: LA, MS, AL (3)
US 13: No new states added
US 15: No new states added
US 19: No new states added
US 20: OR (1)
US 22: No new states added
US 30: No new states added
US 40: No new states added
US 62: TX, NM, OK, AR, KY (5)

None of PA's 3-digit Interstate or US Routes add to this list.

There are no direct routes from PA to AZ, MI, ND, or VT. I-80 and I-90 just miss adding MI to the list by less than one mile, as does US 11 with VT! Closest state not connected is VT.

Total: 43+DC

[TheHighwayMan3561]

Minnesota

I-35: IA, MO, KS, OK, TX
I-90: WA, ID, MT, WY, SD, WI, IL, IN, OH, PA, NY, MA
I-94: MT, ND, WI, IL, IN, MI
US 2: WA, ID, MT, ND, WI, MI (let the debate begin)
US 8: WI, MI
US 10: ND, WI, MI
US 12: WA, ID, MT, ND, SD, WI, IL, IN, MI
US 14: WY, SD, WI, IL
US 52: ND, IA, IL, IN, KY, OH, WV, VA, NC, SC
US 59: IA, MO, KS, OK, AR, TX
US 61: IA, WI, MO, AR, TN, MS, LA
US 65: IA, MO, AR, LA
US 69: IA, MO, KS, OK, TX
US 71: IA, MO, AR, TX*, LA
US 75: IA, NE, KS, OK, TX
US 169: IA, MO, KS, OK
US 212: WY, SD
US 218: MN, IA

Only 27. Ouch.

[FrCorySticha]

Montana's list (duplicates skipped):

I-15: ID, UT, AZ, NV, CA
I-90: WA, WY, SD, MN, WI, IL, IN, OH, PA, NY, MA
I-94: ND, MI

US 20: OR, IA
US 87: CO, NM, TX
US 287: OK
US 2*, 12, 89, 93, 191, 212, 310: All duplicates

# of states: 24

*US 2(W): All duplicates
Including US 2(E) adds VT, NH, ME - 27 states

[FrCorySticha]

US 2: WA, ID, MT, ND, WI, MI (let the debate begin)

While I think both segments should count, I put down numbers for just western US 2 and all of US 2 for Montana. Let others decide what is the "right" number.

[SkyPesos]

I'll keep track with a leaderboard here. Counts will include DC.

1 - Illinois (45)
2 - New York, Pennsylvania (44)
4 - Ohio (41)
5 - Virginia (38)
6 - Indiana (37)
7 - Colorado (35)
8 - Iowa, West Virginia (34)
10 - Massachusetts, Missouri (33)
13 - California, North Carolina (32)
14 - Florida, New Jersey, Texas (30)
17 - Georgia, Maryland, South Carolina (29)
20 - Minnesota, New Mexico, Tennessee, Utah (27)
24 - DC, Kansas, Kentucky, Nebraska, Nevada, Wyoming (26)
30 - Connecticut (25)
31 - Alabama, Arizona, Montana, Nevada, North Dakota, Oklahoma, Rhode Island, Wisconsin (24)
39 - Arkansas, Delaware, Louisiana, Mississippi (23)
43 - South Dakota (22)
44 - Michigan (21)
45 - Oregon (18)
46 - Washington (17)
47 - Maine, New Hampshire (16)
49 - Vermont (5)

[FrCorySticha]

7 - Montana (24)

Sorry, I forgot that US 20 goes through OR. MT is actually 25.

[SkyPesos]

7 - Montana (24)

Sorry, I forgot that US 20 goes through OR. MT is actually 25.

US 20 doesn't enter Kansas.

[FrCorySticha]

US 20 doesn't enter Kansas.

LOL! Miss one on the west, add one on the east. 

[US 89]

Utah appears to get to 26 plus DC:

I-15: CA, NV, AZ, ID, MT
I-70: CO, KS, MO, IL, IN, OH, WV, PA, MD
I-80: CA, NV, WY, NE, IA, IL, IN, OH, PA, NJ
I-84: OR, ID (eastern doesn't count, and it doesn't matter anyway since US 6 covers them)

US 6: CA, NV, CO, NE, IA, IL, IN, OH, PA, NY, CT, RI, MA
US 40: CO, KS, MO, IL, IN, OH, WV, PA, MD, DE, NJ
US 50: CA, NV, CO, KS, MO, IL, IN, OH, WV, MD, VA, DC
US 89: AZ, ID, WY, MT
US 91: ID
US 189: WY
US 191: AZ, WY, MT
US 491: NM, CO

Closest not connected is South Dakota, which is somehow closer than both Washington and Oklahoma.

[kenarmy]

Mississippi:
(NOTE, i excluded 69 from some of them)

AL- US 11, I-20, I-59, US 45, US 98, US 80, I-10, US 78, US 278, US 72, US 82, US 84, US 90, I-22
AK-
AR- US 49, US 61, US 82, US 278, US 425, I-55
AZ- I-10
CA- I-10
CO- US 84             
CT-
DE-
FL- I-10, US 90, US 98
GA- I-20, US 80, US 78, US 278, US 82, US 84, US 11, I-59
HI-
ID-
IL- US 45, US 51, I-55
IN- I-69 (this counts right?),
IA- US 61
KS-
KY- I-69, US 51, US 45
LA- US 425 (gross), US 61, US 11, I-59, US 90, I-10, US 84, I-55, US 51
MA-
ME-
MD- US 11
MI- US 45
MO- I-55, US 61
MN- US 61
MT-
NC-
NE-
NH-
NJ-
NM- I-10, US 82, US 84
NV-
NY- US 11
OK-
OH-
OR-
PA- US 11
RI-
SC- US 78, US 278, 1-20
SD-
TN- *inhale* US 45, US 51, US 61, I-55, I-69, I-269, US 72, US 78
TX- I-10, I-20, I-69, US 80, US 82, US 84, US 90
UT-
VA- US 11
VT-
WA-
WI- US 45, 51, 61
WV- US 11
WY-
D.C.-

So thats 24 for MS. I bet I screwed something up

[SkyPesos]

Mississippi:
(NOTE, i excluded 69 from some of them)

AL- US 11, I-20, I-59, US 45, US 98, US 80, I-10, US 78, US 278, US 72, US 82, US 84, US 90, I-22
AK-
AR- US 49, US 61, US 82, US 278, US 425, I-55
AZ- I-10
CA- I-10
CO- US 84             
CT-
DE-
FL- I-10, US 90, US 98
GA- I-20, US 80, US 78, US 278, US 82, US 84, US 11, I-59
HI-
ID-
IL- US 45, US 51, I-55
IN- I-69 (this counts right?),
IA- US 61
KS-
KY- I-69, US 51, US 45
LA- US 425 (gross), US 61, US 11, I-59, US 90, I-10, US 84, I-55, US 51
MA-
ME-
MD- US 11
MI- US 45
MO- I-55, US 61
MN- US 61
MT-
NC-
NE-
NH-
NJ-
NM- I-10, US 82, US 84
NV-
NY- US 11
OK-
OH-
OR-
PA- US 11
RI-
SC- US 78, US 278, 1-20
SD-
TN- *inhale* US 45, US 51, US 61, I-55, I-69, I-269, US 72, US 78
TX- I-10, I-20, I-69, US 80, US 82, US 84, US 90
UT-
VA- US 11
VT-
WA-
WI- US 45, 51, 61
WV- US 11
WY-
D.C.-

So thats 24 for MS. I bet I screwed something up

It seems like we're not counting I-69 (or other disconnected routes with the same number) except the original section between Indianapolis and Port Huron because it's a disjointed mess that probably won't get finished within the next 30 years. So the only extra state you have is Indiana as the other I-69 states are covered by other routes from Mississippi.

[sprjus4]

The segment of I-69 from the Tennessee / Kentucky state line to Indianapolis will soon be connected to the original, so it would make sense to at least include that.

South of there is a different story.

[TheStranger]

California:

US 101, I-5, US 97: OR, WA
US 199: OR
US 395: NV, OR, WA
US 95: AZ, NV, OR, ID
I-8: AZ
I-10: AZ, NM, TX, LA, MS, AL, FL
I-15: NV, AZ, UT, ID, MT
I-40: AZ, NM, TX, OK, AR, TN, NC
I-80: NV, UT, WY, NE, IA, IL, IN, OH, PA, NJ

21 states!

EDIT: See SkyPesos' response for the correct total of 35 (as I had forgotten about US 6 and 50 in doing this rundown)

[Great Lakes Roads]

RI-

I-95: ME, NH, MA, CT, NY, NJ, PA, DE, MD, DC, VA, NC, SC, GA, FL
I-195: MA
I-295: MA
US 1: ME, NH, MA, CT, NY, NJ, PA, DC, VA, NC, SC, GA, FL
US 6: CA, NV, UT, CO, NE, IA, IL, IN, OH, PA, NY, CT, MA
US 44: NY, CT, MA

In total, Rhode Island has 23 states and DC that are connected via interstates or US highways.

CT-

I-84: PA, NY, MA
I-91: MA, VT
I-95: ME, NH, MA, RI, NY, NJ, PA, DE, MD, DC, VA, NC, SC, GA, FL
I-395: MA
I-684: NY
US 1: ME, NH, MA, CT, NY, NJ, PA, DC, VA, NC, SC, GA, FL
US 5: MA, VT
US 6: CA, NV, UT, CO, NE, IA, IL, IN, OH, PA, NY, RI, MA
US 7: MA, VT
US 44: NY, CT, MA
US 202: DE, PA, NJ, NY, MA, NH, ME

In total, Connecticut has 24 states and DC that are connected via interstates or US highways.

[Great Lakes Roads]

TX-

I-10: CA, AZ, NM, LA, MS, AL, FL
I-20: LA, MS, AL, GA, SC
I-30: AR
I-35: OK, KS, MO, IA, MN
I-40: CA, AZ, NM, OK, AR, TN, NC
I-44: OK, MO
US 54: NM, OK, KS, MO, IL
US 59: AR, OK, KS, IA, MN
US 60: AZ, NM, OK, MO, IL, KY, WV, VA
US 62: NM, OK, AR, MO, IL, KY, OH, PA, NY
US 67: AR, MO, IL, IA
US 69: OK, KS, MO, IA, MN
US 70: AZ, NM, OK, AR, TN, NC
US 71: LA, AR, MO, IA, MN
US 75: OK, KS, NE, IA, MN
US 77: OK, KS, NE, IA
US 79: LA, AR, TN, KY
US 80: LA, MS, AL, GA
US 81: OK, KS, NE, SD, ND
US 82: NM, AR, MS, AL, GA
US 83: OK, KS, NE, SD, ND
US 84: CO, NM, LA, MS, AL, GA
US 85: NM, CO, WY, SD, ND
US 87: NM, CO, WY, MT
US 90: LA, MS, AL, FL
US 180: AZ, NM
US 183: OK, KS, NE, SD
US 190: LA
US 259: OK
US 271: OK
US 277: OK
US 281: OK, KS, NE, SD, ND
US 283: OK, KS, NE
US 285: NM, CO
US 287: OK, CO, WY, MT
US 377: OK
US 380: NM
US 385: OK, CO, NE, SD

In total, Texas has 30 states that are connected via interstates or US highways.

[jflick99]

Since this exercise doesn't work for my current location, I'll do this for my previous homes in KS and SC. I excluded highways that didn't add any new states to prevent these lists from being ridiculously long.

Kansas:
US-24: CO, MO, IL, IN, OH, MI
US-40: UT, CO, MO, IL, IN, OH, WV, PA, MD, DE, NJ
US-50: CA, NV, UT, CO, MO, IL, IN, OH, WV, MD, WV, VA, DC, MD
US-54: TX, NM, TX, OK, MO, IL
US-59: TX, AR, OK, MO, IA, MN
US-159: NE, MO
US-160: AZ, NM, CO, MO
US-81: TX, OK, NE, SD, ND
Excluded 14 redundant US highways and didn't even get to the interstates. 25 states + DC

South Carolina:
US-1: FL, GA, NC, VA, DC, MD, PA, NJ, NY, CT, RI, MA, NH, ME
US-25: GA, NC, TN, KY
US-29: FL, AL, GA, NC, VA, DC, MD
US-52: ND, MN, IA, IL, IN, OH, WV, KY, VA, NC
US-78: TN, MS, AL, GA
US-278: AR, MS, AL, GA
US-301: FL, GA, NC, VA, MD, DE
I-20: TX, LA, MS, AL, GA
Excluded 16 redundant US highways and all other interstates. 28 states + DC

[Mapmikey]

For Virginia interstates....

I-64 - WV, KY, IN, IL, MO
I-77 - SC, NC, WV, OH
I-81 - TN, WV, MD, PA, NY
I-85 - NC, SC, GA, AL
I-95 - FL, GA, SC, NC, MD, DE, PA, NJ, NY, CT, RI, MA, NE, ME
I-495 - MD

22 states via the interstate highway system. I-395 and I-66 also connect to DC, along with I-95.

In the future, we may see I-73 connect to NC and SC, I-785 connect to NC, and I-87 connect to NC.

Finishing Virginia (new states only):
US 11 - LA, MS
US 23 - MI
US 50 - CA, NV, UT, CO, KS
US 52 - ND, MN, IA

33 in total

[SkyPesos]

California:

US 101, I-5, US 97: OR, WA
US 199: OR
US 395: NV, OR, WA
US 95: AZ, NV, OR, ID
I-8: AZ
I-10: AZ, NM, TX, LA, MS, AL, FL
I-15: NV, AZ, UT, ID, MT
I-40: AZ, NM, TX, OK, AR, TN, NC
I-80: NV, UT, WY, NE, IA, IL, IN, OH, PA, NJ

21 states!

There's a bit more
US 6: NV, UT, CO, NE, IA, IL, IN, OH, PA, NY, CT, RI, MA
US 50: NV, UT, CO, KS, MO, IL, IN, OH, WV, VA, DC, MD

Total: 32 states, including DC

I'm not counting decommissioned routes in the leaderboard, but if we included them, US 40 would add DE, US 60 would add KY and US 80 would add GA, which would bring the total up to 35.

[JayhawkCO]

Colorado:
I-25: NM, WY
I-70: UT, KS, MO, IL, IN, OH, WV, PA, MD
I-76: NE
US6: CA, NV, UT, NE, IA, IL, IN, OH, PA, NY, CT, RI, MA
US24: KS, MO, IL, IN, OH, MI
US34: NE, IA, IL
US36: KS, MO, IL, IN, OH
US40: UT, KS, MO, IL, IN, OH, WV, PA, MD, DE, NJ
US50: CA, NV, UT, KS, MO, IL, IN, OH, WV, VA, DC, MD
US84: NM, TX, LA, MS, AL, GA
US85: TX, NM, WY, SD, ND
US87: TX, NM, CO, WY, MT
US138: NE
US160: AZ, NM, KS, MO
US285: TX, NM
US287: TX, OK, WY, MT
US385: TX, OK, NE, SD
US400: KS, MO
US491: NM, UT
US550: NM

34 States + DC.  Closest not connected: ID (124 miles)

Wyoming:
I-25: NM, CO
I-80: CA, NV, UT, NE, IA, IL, IN, OH, PA, NJ
I-90: WA, ID, MT, SD, MN, WI, IL, IN, OH, PA, NY, MA
US14: SD, MN, WI, IL
US16: SD
US18: SD, IA, WI
US20: OR, ID, MT, NE, IA, IL, IN, OH, PA, NY, MA
US26: OR, ID, NE
US30: OR, ID, NE, IA, IL, IN, OH, WV, PA, NJ
US85: TX, NM, CO, SD, ND
US87: TX, NM, CO, MT
US89: AZ, UT, ID, MT
US189: UT
US191: AZ, UT, MT
US212: MT, SD, MN
US287: TX, OK, CO, MT
US310: MT

26 States.  Closest not connected: KS (126 miles)

Chris

[SkyPesos]

Found an older thread that may compliment this thread pretty well. It's about the closest states not directly connected by a single numbered highway.

https://www.aaroads.com/forum/index.php?topic=27031.0

Also, updated the leaderboard:

I'll keep track with a leaderboard here. Counts will include DC.

1 - Illinois (45)
2 - Pennsylvania (44)
3 - Ohio (41)
4 - Indiana (37)
5 - Colorado (35)
6 - Virginia (34)
7 - Missouri (33)
8 - California (32)
9 - Texas (30)
10 - South Carolina (29)
11 - Minnesota (27)
11 - Utah (27)
13 - Kansas (26)
13 - Wyoming (26)
15 - Connecticut (25)
16 - Montana (24)
16 - Rhode Island (24)
18 - Mississippi (23)