Politics has become hi-tech with sophisticated databases, the Internet, TV ads, focus groups and polls.

But a lanky Sangamon County, Ill., lawyer described the essential task of politics in 1840 in a letter to his Whig campaign committee. Make a list of the voters, he wrote, ascertain for whom they will vote, have undecided voters talked to by someone they hold in confidence, and, on Election Day, get all Whig voters to the polls.

Abraham...