My suggestion would be to add the WFL, UFL, and FXFL to that, as well.
Focusing specifically on non-NFL cities/markets across those leagues, and this is the list I made.
Atlantic? East?
- Orlando (WFL, USFL, XFL 2000, UFL, AAF)
- Brooklyn (FXFL)
- Hartford (UFL)
- Norfolk (UFL)
South?
- St Louis (XFL 2020)
- Birmingham (WFL, USFL, XFL 2000, AAF)
- Memphis (WFL, USFL, XFL 2000, AAF)
- Shreveport (WFL)
Central?
- San Antonio (WFL, USFL, AAF)
- Omaha (UFL, FXFL)
- Salt Lake (AAF)
- Oklahoma (USFL)
Pacific? West?
- Sacramento (UFL)
- Portland (WFL, USFL)
- San Diego (AAF)
- Oakland (USFL)
Leftovers
- Honolulu (WFL), skipped for logistic/travel reasons
- Anaheim (WFL) , skipped because LA has 2 NFL teams
- West Palm Beach (FXFL, was supposed to host the Florida Blacktips, but the stadium deal fell apart and it ended up a traveling team)
- Youngstown, OH (FXFL, the Boston Brawlers were going to become the Mahoning Valley Brawlers, but the dissolution of the league meant the team never played in Ohio)
- Hudson Valley (FXFL, technically Fishkill, NY, but same media market as Albany)
NFL Cities in the AAF, XFL, or USFL
- Atlanta (AAF)
- Phoenix (AAF, technically Tempe, but same media market)
- Seattle (XFL)
- Dallas (XFL)
- Houston (XFL, USFL)
- Tampa (XFL, USFL)
- New York/New Jersey (XFL, USFL)
- Washington, DC (XFL)
- Los Angeles (XFL)
- Philadelphia (USFL)
- Pittsburgh (USFL)
- New Orleans (USFL)
- Detroit
Other Medium-Tier Cities/TV Markets
- Harrisburg
- Grand Rapids
- Milwaukee (no stadium, so maybe Madison?)
- Columbus
- Raleigh
- Louisville
- Des Moines
- Spokane
- San Bernardino
- Albuquerque
- Tucson
- West Palm Beach