Are embedded congressional districts illegal?

[Former President tack50]

I mean, this depends a lot on the circumstances, but you'd essencially need a lot of things to happen at the same time. The textbook example like others have mentioned would be if Colorado somehow had only 2 seats, though there are definitely more at the state legislative level.

Trying to think at my times when doing redistricting and experimenting a bit, some donut districts that can be at least somewhat justified (even when other options are 100% better) include (only doing the western half of the US):

>Albuquerque vs Northeast New Mexico
>Colorado Springs vs Southeast Colorado (takes the Denver suburban county of Douglas, so far from an ideal solution)
>Tulsa vs eastern Oklahoma (this can easily be avoided by taking a different set of suburbs, but the donut district is not exactly horrible)

Like I said, a donut district is often not the most ideal solution. However a donut district is not an automatically bad district, it's just a kind of district that is hard to justify. It can be done depending on circumstances, but it needs to be in the right place, with the right population distribution