July 29, Waynesburg, Pa.
Only 20 times since 1876—the year informal record-keeping began—has Waynesburg (50 miles south of Pittsburgh) failed to see rain on July 29. Each year since 1927 a local or larger dignitary has bet his or her hat on zip precip, usually losing. (In parched 1981 the fire department in desperation sprayed hoses heavenward.) Fun includes free ice-cream sundaes served in a 116-foot foil-lined rain gutter set up on Main Street.