I'm with the "add a race in the Northeast" contingent.
Consider: half of the people in the U.S. live in the Eastern Time Zone, 30 % in the Central Time Zone, 15% in the Pacific and only 5% in the Mountain Time Zone.
The five most populous states are: California (3 Nats), Texas (2 Nats), Florida (1 Nats), Illinois (1 Nats), and New York (0 Nats).
Of course, some states have events nearby which must be considered. For example, the event at Norwalk, Ohio (The Summit named facility) has obviated an event in Detroit.
Then, too, Denver has a National Event in part because Denver is the largest city in the Mountain Time Zone and a hub for sports enthusiasts of all types in the region. That's one reason Denver has NFL, NBA, MLB, NHL, Soccer, and Lacrosse franchises!
I would add South Florida as a good future location though I haven't any idea if there is a facility there capapble of upgrade to National Event caliber. Canada ia already in the planning, as it should be. The race in Mexico should be an exhibition, at least to begin with, and should be in Monterrey. Some have suggest Mexico City which is, I believe, the most populous city in the Western Hemisphere; but Monterrey has a racing heritage and is much easier to reach by road from the U.S.
Watching all of this shape up is going to be fun!
Cheers,
Ed