It's hard not to notice a 31 MPH speed limit sign! That's not natural! Never the less, the signs do grab one's attention as you drive through the Heritage Hills neighborhood of Lone Tree, Colorado. The signs are also good conversation pieces if you have visitors riding with you. They almost always ask why the odd number. Actually the signs were intended to get drivers attention and it seems to work.
Then the driver will encounter another unusual sign, Speed Hump! What happened to Bump? Whatever works.