A LOT of Americans made automobiles in 1900-1930, here are a some, a couple of them I've never heard of

1895 Electrobat II... and for the trivia buffs, it was the winner of the first car race in America

Geronimo's Cadillac is how it was presented, but I doubt that he owned it... it's probably a photo op planned picture

Teddy Roosevelt in a Fawick Flyer at the Sioux Falls Railroad Depot. Only 5 were ever built

A Moosejaw Standard

A Saxon

1915 Monroe

1916 Woods Mobilette

1917 Apperson Jack Rabbit

This is a 1917 Geronimo

1920 Barley Roamer roadster

1923 Arkansas Climber

1952 Maverick

A Powell, made in LA

All of these are only a fraction of the interesting defunct manufacturers on the Jalopy Journal thread that challenged car guys every where to post photos and information about car makers that went out of business long ago: http://www.jalopyjournal.com/forum/showthread.php?t=397594