The Hamilton Motors Company was founded in 1917 by Guy Hamilton, after his Grand Haven, Michigan Alter Motor Car Company went bankrupt. The company produced only one car, the Model A-14, which was a four-cylinder, 28 hp touring car with a 112-inch (2,800 mm) wheelbase. He promised to make a six-cylinder car, but never did.

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article needs additional citations for verification. (October 2011) This article relies largely or entirely on a single source. (October 2011)

In 1918, the H. A. Oswald Engineering Company tried to resurrect the Hamilton as the Oswald, but it failed. However, Hamilton's Alter truck was produced until 1921.