The actual location of Acme Acres doesn't seem to be firmly defined, as it has been its own island city municipality. In various episodes, Acme Acres is set in multiple locations, but it appears to be most commonly placed in California. In both the cartoon "Cross Country Kitty" and in the Tiny Toon movie How I Spent My Vacation, it is in California, probably near Los Angeles.
However, in the cartoon "Never Too Late to Loon", it is somewhere in Missouri. There is also another reference in the Spring Break Special that puts Acme Acres approximately a thousand miles from Ft. Lauderdale, Florida, along Interstate 95, which follows the eastern coastline of the United States. This would put Acme Acres somewhere near Philadelphia or possibly New York City. Also, in the Christmas special, it snowed in Acme Acres.