Here is an interesting article discussing what zoo was first to open in the U.S. and the answer is complicated. In our book, America's Top 100 Zoos & Aquariums, @Tim Brown and I made the case that Central Park Zoo (1864) was first, followed by Lincoln Park Zoo (1868), Roger Williams Park Zoo (1872) and then Philadelphia Zoo (1874) in 4th place and we are cited as a reference in the essay on the link below. However, due to having a charter in place in 1859, 'Philly' is often called 'America's first zoo'. This article analyzes that statement and there is even an opportunity to vote! Zoo Was First—New York or Philly?