Closest pairs of 3di's with the same number

[KCRoadFan]

Two major cities along the Gulf Coast - Biloxi, MS and Pensacola, FL - are both connected to I-10 by spurs numbered I-110, which are 109 miles apart.

I-235 in Wichita, KS and I-235 in Oklahoma City are 150 miles apart on I-35.

Before the section of the Maine Turnpike north of Portland was renumbered from I-495 to I-95, the south end of that stretch was just 70 miles along I-95 from the northern terminus of I-495 in Massachusetts.

Aside from those, what are some of the closest pairs of different 3-digit interstates (3di's) that happen to share the same number?

[hotdogPi]

I-291 in Massachusetts and Connecticut.

[MATraveler128]

I-291 in Massachusetts and Connecticut.

That is indeed the closest pair. After that is probably the I-395s in MD and VA/DC and then the I-695's in DC/MD are 31 miles apart although that will change once I-695 in DC is decommissioned.

I-195 in Maryland will be 30 miles from the future I-195 in DC (presently I-395)

[ilpt4u]

Since KYTC and INDOT haven't gotten final approval to sign the unified I-265, probably the 265s that are connected by an interstate-standard toll bridge and tunnel across the Ohio and under a hill in Kentucky

AASHTO granted permission to sign it, but FHWA apparently wants some (minor) things addressed before giving the final green light to sign and approve the unified I-265 designation

[Ned Weasel]

I-470 in Kansas and Missouri are only about an hour apart from each other.  But that's more than 30 miles, so they don't win.

[Hobart]

This is the technicality to end all technicalities, but apparently I-676 ends at the ramps at Interstate 95 in Downtown Philadelphia, and starts again at the New Jersey state line, halfway through the bridge, with a different signed orientation. This is because I-676 isn't actually up to standards between I-95 and the bridge; the only reason it's still signed there is for convenience reasons for motorists, but Pennsylvania DOT has it stopping at I-95.

Therefore, Interstate 676 in Pennsylvania and Interstate 676 in New Jersey are two separate 3dis with the same number, that stop 4,000 feet from each other. Although the intent is for it to be one interstate, legally it's two, in two different states, which allow them to share a number.