The Crack in Space | Philip K. Dick
All kinds of problems erupt when a repairman discovers that a hole in a faulty Jifi-scuttler leads to a parallel world, with Jim Briskin, campaigning to be America's first black president, determined to use the new world as a solution to Earth's overpopulation problem, and billionaire mutant George Walt hoping to seize control of it, but the other Earth turns out to be inhabited. Reprint. 10,000 first printing.