Let's do this: instead of any one particular sport, let's use a fictional sport that we'll say is equally popular across the entirety of North America. Because certain sports are more popular in certain areas and less popular in others (hockey, football, etc.) the map would look different depending on the sport. So, this is my ideal 32-team league in any given sport (without multiple teams in a single city, just for fun):

Note - this is based on a 2020 perspective, as if I was deciding all 32 at once.
1. New York - Naturally. Largest metro in the US and Canada, biggest sports market as well, it just makes sense.
2. Los Angeles - America's second city, LA is just like New York, certainly large enough for two teams but for now just one.
3. Chicago - Again, obvious pick.
4. Toronto - International pick, Toronto is similarly large and has a good history with supporting sports teams.
5. Dallas - large metro, Dallas-Fort Worth is filled with people.
6. Houston - You could flip Dallas and Houston and I'd be fine. Very similar cities, both deserve a team.
7. Philadelphia - Time to hit another obvious pick, Philly's more than large enough to have a team.
8. San Francisco/Oakland/San Jose - The Bay Area is very deserving of a team and again has the population to support a team. I tend to prefer San Francisco to use, then San Jose as a second team, but any city works.
9. Washington - Again, the DC metro is very large and the nation's capital deserves a team.
10. Miami - Large TV market, the only issue is possible transplant fans.
11. Boston - Natural choice, large market, history with sports.
12. Minneapolis/St. Paul - The Twin Cities just make sense.
13. Denver - Colorado and Denver specifically fill a geographical niche that no other city can fill.
14. Seattle - The PNW is a huge corridor and a team in Seattle fills that very nicely.
15. Atlanta - Large market, but fickle fans and a less-than-stellar history of supporting teams. But still, that TV market cannot be ignored.
16. Cleveland/Columbus - Ohio really only needs one team, and I tend to choose Cleveland, but you really can't go wrong here. Cincinnati works well a second Ohio city, but not the first in my opinion.
17. Detroit - Despite some economic troubles, the city of Detroit is still a large one and supports all four teams quite well.
18. Phoenix - Massive city, massive market, only concern is transplants.
19. St. Louis/Kansas City - Again interchangeable, a Missouri team will do well regardless of where you put it. I personally don't see the need for a team in both cities, however.
20. Tampa Bay/Orlando - A Central Florida team usually works out, filling in where Miami's appeal wears off.
21. Pittsburgh - While the city is smaller than other markets (and shrinking), the history the city has cannot be denied.
22. Charlotte/Raleigh - As much as I hate to admit it, the two serve the same geographical niche. That said, willingly choosing Raleigh over Charlotte is stupid simply because of the population and corporate money flowing through Charlotte, but the two are similar.
23. Nashville/Memphis - Much like North Carolina, Tennessee has two large enough cities, but not large enough to warrant having one in each. Pick your favorite.

At this point we've hit the cutoff I have for cities that you should really have, so the following cities can be picked at will to fill out 32.

24. San Diego - California's population is more than large enough to let San Diego have their own team.
25. Indianapolis - This city would be much higher if it wasn't surrounded by much larger markets in Chicago, Detroit, and Ohio.
26. Baltimore - Just too close to DC to warrant its own team in sports like basketball and hockey, but baseball and football have made it work.
27. Portland - A quirky PNW city that I think could work quite well, provided the right conditions.
28. San Antonio - A third Texas team requires the right sport, but it works when it works.
29. Sacramento - Just a little too close to the Bay Area and a little too small to be available for any more than two leagues, in my opinion.
30. Vancouver - If you're going to have a second Canadian team, Vancouver is the way to go. The French-Canadian Montreal has its own issues that make Vancouver a safer choice.
31. Milwaukee - See Indianapolis, but compounded by the fact that Milwaukee is tiny compared to it.
32. New Orleans - Just a rough market. Honestly the only team they can support seems to be the Saints, it would be a disaster for any other league.
33. Buffalo - A small Rust Belt city that's past its heyday? No thanks.
34. A second team in Missouri/Ohio/the Bay Area. Not really necessary, but doable.
35. Louisville - Same issues as Indy and Milwaukee, but has trouble with size and also doesn't have a sporting history like the others.
36. Newark - It's only here because I can't add a second New York team.
37. Montreal - Too many issues with corporate money and the French-Canadians. Hockey works perfectly, but other sports have a rough time.
38. Norfolk/Virginia Beach - It's like Raleigh, but with even less upside!

So there it is. If you ask me, cities like Jacksonville, Salt Lake City, and Las Vegas shouldn't be in the conversation at all, but clearly the leagues that have teams there see something about them that makes it worth being there.

Ooooo. This could be fun. I don't duplicate cities (where's the fun in that?). The 32 I tend to end up with, in an alphabetical order:
1) Atlanta
2) Baltimore
3) Boston
4) Charlotte
5) Chicago
6) Cincinnati (well, that's the plan. I always start in the past with Dayton, who then succeeds, and I can't justify moving them to Cincinnati)
7) Cleveland
8) Dallas
9) Denver
10) Detroit
11) Houston
12) Indianapolis
13) Kansas City
14) Los Angeles
15) Miami
16) Milwaukee
17) Minneapolis/St. Paul
18) Nashville
19) New Orleans
20) New York
21) Orlando/Tampa
22) Philadelphia
23) Phoenix
24) Pittsburgh
25) Portland
26) San Antonio
27) San Diego
28) San Francisco
29) Seattle
30) St. Louis
31) Toronto
32) Washington