Angel Island is an island in San Francisco Bay. The entire island is included within Angel Island State Park, administered by California State Parks. The island, a California Historical Landmark, has been used by humans for a variety of purposes, including seasonal hunting and gathering by indigenous peoples, water and timber supply for European ships, ranching by Mexicans, United States military installations, a United States Public Health Service Quarantine Station, and a U.S. Bureau of Immigration inspection and detention facility. The Angel Island Immigration Station, on the northeast corner of the island, which has been designated a National Historic Landmark, was where officials detained, inspected, and examined approximately one million immigrants, who primarily came from Asia. Under the Chinese Exclusion Act of 1882, the first United States law to restrict a group of immigrants based on their race, nationality, and class, all arriving Chinese immigrants were to be examined by immigration or customs agents.

San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the cities of San Francisco, San Jose, and Oakland.