Historically, Iowa voters pick their neighbors for president.

In an excellent summary of Iowa caucus history, David Yepsen, a political columnist for the Des Moines Register, offers an explanation for some important patterns in caucus voting:

One pattern that appears to be developing in the Iowa caucuses is a preference for Midwestern, or at least rural-oriented candidates. George McGovern of South Dakota, Walter Mondale of Minnesota, Richard Gephardt of Missouri have all done well in Iowa Democratic caucuses.

Harkin, of course, is from Iowa and won big there with 77% percent of the vote. Ultimately, he placed fourth in New Hampshire and his candidacy ended.

Take from this what you want, but if the pattern holds Obama has an edge if only because he is from a neighboring state, Illinois.

As the chart below shows, those neighborly picks don’t always pan out further down the campaign trail. The same is true for some Massachusetts candidates who got New Hampshire votes because they came from the “state down under.”

See my other comment: Iowa and New Hampshire’s track records in picking the Democratic nominee.

The Iowa – New Hampshire Connection Prepared by Rake Morgan for the Hillary Clinton Quarterly
Election Year	Iowa Caucus Winner	New Hampshire Winner	Democratic Nominee
2004	John Kerry	John Kerry	John Kerry
2000	Al Gore	Al Gore	Al Gore
1996	Bill Clinton (incumbent)	Bill Clinton	Bill Clinton
1992	Tom Harkin	Paul Tsongas	Bill Clinton
1988	Dick Gephardt	Mike Dukakis	Mike Dukakis
1984	Walter Mondale	Gary Hart	Walter Mondale
1980	Jimmy Carter (incumbent)	Jimmy Carter	Jimmy Carter
1976	Jimmy Carter	Jimmy Carter	Jimmy Carter
1972	Ed Muskie	Ed Muskie	George McGovern