Recently re-opened to the public after three years of renovation, San Francisco's Angel Island Immigration Station was once known as the "Ellis Island of the West" by locals, and the somewhat grander "Guardian of the Western Gate" by Immigration Services. Unlike the Ellis Island of the East, Angel Island was used to enforce the 1882 Chinese Exclusion Act and detain hundreds of thousands of Asian immigrants, who were held on the island for anywhere from two weeks to two years. Also unlike its cousin in New York, the Angel Island museum doesn't doesn't give access to immigration records. Instead, it recreates the experience of living in the complex's barracks, and preserves fascinating details like poems carved on the walls by Chinese detainees. If you happen to be going to San Francisco soon, the museum can be visited by guided tour.
Angel Island barracks, then and now