I guess the problem for F1 in the US is the media and the marketing.
Be it business, politics, sport or just general news the US media just doesn't seem to get the fact that, while very important, it isn't the only place in the world. Spend a little time in the States and you very soon loose touch with what is going on in the rest of the world unless it is a major disaster or in some way directly affects the US or US people. The pity of it is when Americans travel, or when you get a chance to talk to them on their home turf they are wonderful people.
But we shouldn't complain, one of the people most to blame for the way that is developing was born in Australia and got his power base from here. Lot to answer for our Rupert.

The US has produced some great F1 people going back as far as Harry Schell, Phil Hill, Dan Gurney, Pete Revson, Mario Andretti etc. and a lot of technical people and ideas that have changed the game.
F1 was popular in the US for quite a while with events like Sebring, Watkins Glen, Long Beach, Las Vegas and the Indy Road course. Probably the reason it became less popular was the great racing provided by the Champ Car series for many years which gave America home grown open wheel racing at a high standard. The war between Champ Car and Tony George sort of killed off both the CC and IRL as real competitive series and open wheel racing lost it's profile.
The more recent people who have tried to cross over from US racing to F1 just haven't made the grade unless you count Jacques Villeneuve.