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 1905 Locomobile 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 Moose Jaw Standard

The Moose Jaw Standard hailed from the town of the same name in Saskatchewan, Canada. A group of citizens from the town hired an engineer, acquired a factory and bought enough components from American suppliers to manufacture 25 cars. Only five were completed, with one each going to the backers of the enterprise. The remaining parts were sold off, the engineer paid off and the project was wound up. One of the five cars still survives today. (thanks Graham!)

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