Back Roads to the White House

Sure, Washington, D.C., has the U.S. Capitol, the White House, Ben's Chili Bowl and a whole bunch of other important American landmarks.
But every four years, the center of the political universe shifts to America's Heartland.
It all starts at a crossroads in Des Moines.
There, the westbound interstate leads toward Denver, home of the 2008 Democratic National Convention. The northbound interstate goes straight to Minneapolis-St. Paul, home of the 2008 Republican National Convention.
The candidates know they're not going to get anywhere -- certainly not to 1600 Pennsylvania Avenue -- if they can't survive the potholes in downtown Des Moines, the speed bumps in Davenport and the mind-numbing drives past the farm fields between Cedar Rapids to Dubuque.
These are the back roads to the White House, scenic highways and byways often littered with broken-down bandwagons, crashed ambitions and campaigns that have simply run out of gas.