The winner of the U.S. presidential election will be determined by about 17 swing counties, with a total of about 500,000 swing voters between them. The American public has heard that 12 swing states will determine who will be the next president. But a book, Presidential Swing States: Why Only Ten Matter, by Hamline University Professor David Schultz, who also edits the Journal of Public Affairs Education, predicts a very small number of America’s 3,142 counties and county equivalents will tip the balance. In Ohio, it’s Hamilton County, home to Cincinnati; In Pennsylvania, the key counties are Bucks and Chester...