Final answer:
Ellis Island was the first agency to open in New York City and served as the port of entry for millions of immigrants.
Step-by-step explanation:
The agency that was the first to open its doors in New York City was Ellis Island. It opened in 1892 and served as the port of entry for about half of the immigrants to the United States in the next two decades. Ellis Island processed over 12 million people during the 62 years it was open. Immigrants who could afford a first or second class ticket were able to bypass the inspection at Ellis Island and were inspected aboard the ship. The Federal government believed that more affluent immigrants were less likely to be a burden on the state.