Rain Follows the Plow

"Since the territory [of Colorado] has begun to be settled, towns and cities built up, farms cultivated, mines opened, and roads made and travelled, there has been a gradual increase in moisture.... I therefore give it as my firm conviction that this increase is of a permanent nature, and not periodical, and that it has commenced within eight years past, and that it is in some way connected to the settlement of the country, and that as population increases the miosture will increase."

-- Professor Cyrus Thomas, noted U.S. ethnologist and entomologist, circa 1870s  

"Rain Follows the Plow" was a pseudoscientific idea in the American west (and also South Australia), originating as a marketing campaign to entice Americans to move west.

Via "Cadillac Desert: The American West and Its Disappearing Water" (1993) by Marc Reisner (highly recommended -- it was voted one of the 100 best nonfiction books written in English during the 20th century.)