Pickup trucks. The #1 selling vehicles in the US year after year are pickup trucks. Those aren't really needed or desired (due to size) in places like NYC and SF.

In the midwest, however, Pickup trucks are everywhere. In my suburban Detroit neighborhood, looking outside, probably half of the houses have a truck parked in the driveway. I'm thinking of getting one soon. I don't usually have a need for one, but a small old S-10 (Chevy) or Ranger (Ford) would be handy sometimes.

It was the same when I lived in Indiana. I was in the minority driving a sedan.

American trucks outsell the foreign competitors handily, though Toyota is catching up with the Tundra.

My guess would be: compact cars are more desired in very urban areas for many reasons (size when parking, fuel efficiency in an area where it is more expensive); less trucks (truck workhorses are overwhelmingly American); and a higher concentration of rich people so more German imports.

My guess is that people there have less connection to the Detroit 3. I live in Grand Rapids, which is second only to Detroit in their list for having the highest percentage of American brands, and I got a few sideways glances when I purchased my Civic (even though it was manufactured in Indiana). Like any other Michigan resident, I have quite a few acquaintances that are somehow connected to the auto industry. Also, I know that GM gives out some pretty good discounts for their employees, which they can share with family. I'm assuming that other brands are similar.

One thing that I didn't know prior to moving to California is that if your car meets certain specifications, it gets a sticker that allows you to drive in diamond lanes (carpool lanes), regardless of the number of passengers. I imagine that this, combined with foreign brands' early investment in hybrids, is a factor in the popularity of foreign brands in California, at least.

I don't have any hard research, but I suspect it is mostly style and ego. BMWs are generally perceived as higher status and more stylish than Cadillacs.

Edit - I speaking mostly of cars and middle-weight SUVs. Pickup trucks, as noted in a sibling, might skew the rural areas back to the domestic end of the spectrum.

Part of that is a history of poorly constructed domestic cars (relative to Japanese imports, anyway). My personal experience bears this out... My most reliable car to date is a Lexus RX330. I owned a used Miata that was better than average. And a used Pontiac sedan that needed a new engine at 75,000 miles. I currently drive a Wrangler, and have my fingers crossed that it proves Americans can build reliable cars. Time will tell.