Who let the Immigrants on the east coast in the late 1800s entry into the US?

In the late 1800s, immigrants arriving on the East Coast, particularly through Ellis Island, were admitted to the United States under the authority of the federal government. The Immigration Act of 1891 established a federal system for processing immigrants, which included health inspections and legal evaluations. Local authorities and organizations often assisted in the process, but ultimately, it was the U.S. government that set the policies and regulations governing entry.