Answer: 40%
According to the National Parks of New York Harbor, “it is believed that approximately 40 percent of America’s population can trace their ancestry through Ellis Island.” Situated at the mouth of the Hudson River, Ellis Island is considered the “gateway to America”. Below are pictures of one of America’s most famous monuments.

First Ellis Island Immigrant Station, opened on January 1, 1892. Built of wood, it was completely destroyed by fire on June 15, 1897.
Immigrants coming up the boardwalk from the barge, which has taken them off the steamship company’s docks, and transported them to Ellis Island. The big building in the background is the new hospital just opened. The ferry-boat seen in the middle of the picture runs from New York to Ellis Island.

Public Health Service physicians checking immigrants arriving to the United States for signs of illness. The immigration law of 1891 made it mandatory that all immigrants coming into the United States undergo health inspection by Public Health Service physicians. The largest inspection center was on Ellis Island in New York Harbor. In this 1910 photo, physicians are looking at the eyes for signs of trachoma. Credit: NIH.