Final answer:
Most Asian immigrants entered the United States through Angel Island in San Francisco Bay, while European immigrants arrived via Ellis Island in New York City.
Step-by-step explanation:
The primary location where most Asian immigrants entered the United States was through Angel Island, which is located in San Francisco Bay, California. Angel Island served a similar function to New York City's Ellis Island, which was the main entry point for European immigrants. Many Asian immigrants came to the United States during significant periods such as the mid-nineteenth century Gold Rush and later during the construction of the Transcontinental Railroad, which sought labor for its completion. In contrast, immigrants from Vietnam arrived predominantly after 1975 due to political upheaval and as refugees seeking asylum. Today, Angel Island stands as a national historic landmark in recognition of its role in the immigration history of the United States.