Los Angeles Mayor Eric Garcetti knows all too well that people confuse Rodeo Road with the Rodeo Drive ... but that's NOT why the former was renamed Obama Blvd.
We got hizzoner at USC's Galen Center in downtown L.A. and our camera guy just had to know -- was the reason for the change that untold numbers of folks ended up accidentally going to glitzy Beverly Hills instead of south L.A. or vice versa.
Our photog's question triggered an LOL from the Mayor ... who got in on the joke before getting all presidential on us. Garcetti explained Obama made a historic visit on the Road long before he was POTUS ... and that's what triggered the move for the switch.
Watch the vid ... our guy has another trick up his sleeve in getting Garcetti to spill the beans on whether he's running for Prez in 2020.