If the idea of presidential blood—even just a little—flowing through your veins gets your heart rate going, you might want to sit down for this: 100 million Americans have family ties to one or more of the 42 US presidents. Gary Boyd Roberts, author of Ancestors of American Presidents (Boyer, out of print), says almost anyone with New England ancestry is probably connected to dozens of presidents. Those with Quaker or Southern roots have a pretty good chance, too.

Perhaps you've heard a family story about your great-great-uncle being the cousin of Ulysses S. Grant. Maybe all those Washingtons or Lincolns in your family tree have raised your suspicions, or you just wonder whether you have a familial connection to the highest office in the land. Whatever your reasons, there's no better time to track down possible presidential forefathers than this election season.

1. Start your own genealogy campaign.

Before you begin marching around the house singing "Hail to the Chief," sort out what you already know about your family history. Though you may be absolutely confident you can make that connection to Thomas Jefferson, you first have to research your own genealogy, advises professional genealogist Rhonda McClure. "For beginners who have heard they are related to one of the presidents, I always tell them the same thing: It is important to research your own line thoroughly," she says. Only then will you start to see familiar names and localities in the ancestries of the presidents.

If there's a president in your family's past, he's most likely a distant cousin, and the connection lies somewhere in the 1700s or earlier, McClure notes. To speed your search, start with the ancestral line you already know the most about—the one that you've traced back the furthest.

Norris Taylor, a Los Angeles family historian who has traced his lineage to 13 presidents, says it also helps to research your immigrant ancestors' grandchildren and their spouses. "Many [published] ancestral lines seem to stop short of an immigrant, in many instances by about three generations," he says. Visit Taylor's online "presidential gallery" members.tripod.com/~ntgen/bw/ pres_atop.html to see the results of his chief-executive roots research.

When you start searching, be prepared for disappointment—not everyone, of course, has presidential ancestors. Those who descend from German or Scots-Irish immigrants have only a "slim chance" of finding a president in their family trees, Roberts says. And don't put too much stock in family lore about White House links. Those notions likely stem from the 19th-century assumption that anyone with a president's surname must be related to him, says Roberts. "Most of these are false."