MESA, Ariz.--The changes to my neighborhood were subtle at first. More people wore scuffs and tank tops at the supermarket, and the lines were longer owing to the complexities of determining what is a permissible food stamp purchase. Three dozen cupcakes from the bakery qualify, but a barbecued chicken from the deli does not. Those of us who bake our own cupcakes and broil our own chicken waited as cashiers tried to make sense of federal welfare policy.

The landscape, once impeccably maintained, began taking on a littered look....