Parent/sibling or sibling/sibling concurrencies

[ilpt4u]

IL gives us another one, in the Western part of the state:

US 136 and IL 336, between Carthage, IL and Tennessee, IL for now

[Flint1979]

IN-550 either has a gap, or is an unsigned concurrency with US 150 (and partially with US 50) between Loogootee and Wheatland

The Wiki article for IN-550 claims it is gapped, and not an unsigned concurrency. But that is good old Wikipedia for ya

Indiana's gaps really are gaps. There are at least three flavors of IN 101.

I'm assuming Indiana uses the same number for different sections of highway is because of the way the highways are numbered in Indiana. Indiana's state highways are setup the same way the U.S. highways are going across the country with the even numbers going east and west and the higher numbers being in the south and the same for north-south and the higher numbers being in the west. There are some exceptions though and those are the diagonal routes SH 37, SH 47, SH 56, SH 57, SH 62, and SH 67.