How many immigrants crossed through the gateway predecessor of the first American immigration station?
Castle Clinton: Castle Clinton or Fort Clinton, previously known as Castle Garden, is a circular sandstone fort now located in Battery Park, in Manhattan, New York City. Castle Clinton:  It is perhaps best remembered as America's first immigration station (predating Ellis Island), where more than 8 million people arrived in the U.S. from 1855 to 1890. Ellis Island: Ellis Island, in Upper New York Bay, was the gateway for over 12 million immigrants to the United States as the nation's busiest immigrant inspection station for over sixty years from 1892 until 1954.
12 million