Earlier this week, the Chicago Park District had tested the fountain, but crowds gathered Sunday for a festival and the 2 p.m. switch-flipping for the official turn on.
Live music, food and family activities were also offered to celebrate the annual event.
The spectacular water display is powered by a 225 horse power motor that drives the main pump, which, in turn, shoots roughly 8,000 gallons of water through the fountain each minute. This runs from 8 a.m. to 11 p.m. daily.
At the top of each hour starting at 9 a.m. (with a final showing at 10:35 p.m.), two more pumps pitch in for an even bigger 20 minute show. The center jet (which reaches 150 feet into the air) gets its own pump for those performances.
At its peak, with all three of these pumps running, Buckingham Fountain has 15,000 gallons of water shooting out of it every minute, said Eric Kelmar, the Chicago Park District's assistant chief operating engineer for the lake front region.