Jeep and Hummer are not car companies. Jeep is owned by Daimler-Chrysler and Hummer is owned by the big GM itself.
GM will never fold because Fords are crap. They're just in a bit of a slump right now cause Daimler-Chrylser is beating the snot out of both of them.
And almost any car you can buy in America was assembled in America by Americans paying American taxes.
Oh, and interestingly enough, Ford owns Volvo, Land Rover, Lincoln/Mercury, Mazda, and Jaguar; Daimler-Chrysler owns Jeep, Dodge, Mercedes, and Hyundai, and GM has Chevy, Pontiac, Buick, Saturn, Subaru, Saab, GMC, Cadillac, and the ever popular Daewoo.
Honda owns Honda, Toyota owns Toyota, and Nissan owns Nissan.