Newly released figures show the National September 11 Memorial has quickly become one of the city's most visited sites.
Officials say over 4.5 million trips have been made to the memorial since it opened to the public on September 12, 2011.
Visitors came from all 50 states and more than 170 countries.
Meanwhile, work is expected to resume on the adjacent National September 11 Museum, after an agreement over costs was finally reached.
The museum is now expected to open by the end of 2013.