<Tr> <Th> Added to NRHP </Th> <Td> October 14, 1971 </Td> </Tr> <Tr> <Th> Designated NHLD </Th> <Td> December 9, 1997 </Td> </Tr> <P> Angel Island Immigration Station was an immigration station located in San Francisco Bay which operated from January 21, 1910 to November 5, 1940, where immigrants entering the United States were detained and interrogated . Angel Island (California) is an island in San Francisco Bay . It is currently a State Park administered by California State Parks and a California Historical Landmark . The island was originally a fishing and hunting site for Coastal Miwok Indians, then it was a haven for Spanish explorer Juan Manuel de Ayala . Later, it was developed as a cattle ranch, then, starting with the Civil War, the island served as a U.S. Army post . During the island's Immigration Station period, the island held hundreds of thousands of immigrants, the majority from China, Japan, India, Mexico and the Philippines . The detention facility was considered ideal because of its isolated location, making it very easy to control immigrants, contain outbreaks of disease, and enforce the new immigration laws . The station is listed on the National Register of Historic Places under the title Angel Island, U.S. Immigration Station, and is a National Historic Landmark . </P> <P> Angel Island Immigration Station, sometimes known as "Ellis Island of the West," began construction in 1905 in an area known as China Cove . The main difference between Ellis Island and Angel Island was that the majority of the immigrants that traveled through Angel Island were from Asian countries, such as China, Japan, and India . The facility was created to monitor the flow of Chinese immigrants entering the country after the implementation of the Chinese Exclusion Act in 1882 . The Act only allowed entrance to merchants, clergy, diplomats, teachers, and students, barring laborers . The Act did give the government an idea of how to begin to regulate immigration, and realize the potential effect of immigration on the economy . </P>

When did the angel island immigration station open why was it built