Many years ago, as a college Republican, I spent one summer in Austin working for a candidate in a special election for the Texas Senate. My hometown was a liberal enclave with many college students — unwashed, longhaired, pot-smoking students, it seemed to me — who were predominantly Democrats. The more students who came out to vote, the less likely our candidate was to win.

But our campaign strategists came up with a plan. They sent mailings to all the registered voters in precincts near the campus. Many cards came back because the addressee had moved, as college students often do. Voters no longer at the address on file with election authorities were not eligible to vote.