Distribution frequency of single state mainline interstate lengths.

[Duke87]

I got an itch, so:

<100 mi         77
100-199 mi   73
200-299 mi   45
300-399 mi   28
400-499 mi   10
500-599 mi   2
600-699 mi   1
700-799 mi   1
800+ mi         1


Notes:
- this includes the Hawaii interstates but not the Alaska or Puerto Rico ones
- this does not include I-69's very unfinished pieces south of KY due to it not being determinate how long they may eventually be.
- this does not include proposed sections of interstate where nothing within the state is yet signed (e.g. I-11 AZ)

[english si]

The 15 routes over 400 miles are (according to the FHWA logs):

I-15 UT 400.60 mi
I-80 WY 402.59 mi
I-80 NV 410.45 mi
I-90 SD 412.75 mi
I-40 NC 420.06 mi
I-70 KS 423.60 mi
I-70 CO 450.18 mi
I-80 NE 455.18 mi
I-40 TN 455.41 mi
I-25 NM 462.12 mi
I-75 FL 470.70 mi
I-35 TX 504.15 mi (includes I-35E)
I-90 MT 544.70 mi
I-5  CA 796.53 mi
I-10 TX 881.00 mi

This has a slightly different distribution to what you have.

[I-55]

The 15 routes over 400 miles are (according to the FHWA logs):

I-15 UT 400.60 mi
I-80 WY 402.59 mi
I-80 NV 410.45 mi
I-90 SD 412.75 mi
I-40 NC 420.06 mi
I-70 KS 423.60 mi
I-70 CO 450.18 mi
I-80 NE 455.18 mi
I-40 TN 455.41 mi
I-25 NM 462.12 mi
I-75 FL 470.70 mi
I-35 TX 504.15 mi (includes I-35E)
I-90 MT 544.70 mi
I-5  CA 796.53 mi
I-10 TX 881.00 mi

This has a slightly different distribution to what you have.

I-20 in Texas is 636.08 miles. Otherwise, the addition of I-15 to the 400 mile club is correct.

[SkyPesos]

Ohio:
<100 mi        2 (I-74, 76)
100-199 mi   1 (I-77)
200-299 mi   5 (I-70, 71, 75, 80, 90)
Average length: 178.96 mi
Median length: 218.58 mi

Indiana:
<100 mi        1 (I-94)
100-199 mi   5 (I-64, 70, 74, 80, 90)
200-299 mi   1 (I-65)
300-399 mi   1 (I-69)
Average length: 176.09 mi
Median length: 156.44 mi

[vdeane]

New York 2dis:
<100 mi: 4 - I-78, I-84, I-95, I-99
100-199 mi: 2 - I-81, I-88
200-299 mi: 1 (for now?) - I-86 (present)
300-399 mi: 2 (hopefully someday 3) - I-86 (full buildout), I-87, I-90

New York 3dis:
<10 mi: 12 (formerly 13) - I-478, I-878, I-781, I-587, I-787, I-290, I-590, I-790, I-890, I-990, I-295, I-695, I-895
10-19 mi: 3 (soon to be 2) - I-678, I-481, I-690
20-29 mi: 2 - I-684, I-190
30-39 mi: 3 - I-278, I-287, I-490
40-49 mi: 0
50-59 mi: 0
60-69 mi: 0
70-79 mi: 2 - I-390, I-495

[gonealookin]

Nevada:

I-80:  410.458 mi.
I-15:  123.762 mi.
I-11:  54.193 mi.
I-580:  35.050 mi.
I-215:  11.173 mi.
Total:  634.636 mi.

By county (all I-80 unless noted):
Clark:  189.128 mi. (I-15 + I-11 + I 215)
Elko:  132.674 mi.
Pershing:  75.070 mi.
Washoe:  70.221 mi. (44.462 mi. I-80 + 25.759 mi. I-580)
Humboldt:  61.358 mi.
Churchill:  27.710 mi.
Lander:  26.855 mi.
Eureka:  25.815 mi.
Lyon:  15.908 mi.
Carson City (not a county):  9.291 mi. (I-580)
Storey:  0.606 mi.
Douglas, Esmeralda, Lincoln, Mineral, Nye, White Pine:  none

Most miles, single interstate, single county:
I-80 in Elko County:  132.674 mi.
I-15 in Clark County:  123.762 mi.

Source:  NDOT's "State Maintained Highways of Nevada", January 2026   

[Duke87]

I-20 in Texas is 636.08 miles. Otherwise, the addition of I-15 to the 400 mile club is correct.

OK yeah I had I-15 UT categorized in 300-399 based on the last exit being 398 and it being less than 2 miles from the state line. 'Lil rounding error messes with that.