Citi Bike opened its registration to the public today and, as of 3 pm EST, it had already sold about 2,500 memberships, according to Transportation Nation. As part of the initial promotion, Citi Bike offered a handful of added benefits to the first members, including a special “Founding Member” key.

As a comparison, Capital Bikeshare, the United States biggest program, has about 20,000 total members. Based on these first day membership rates, we can expect that Citi Bike will surpass the 20,000 mark within the first few months of operation, if not sooner.

Purchase your Citi Bike membership here.