This touring style of campaigning didn’t take place until the U.S. had developed a comprehensive railroad system in the latter 19th century. Before then, candidates courted the mostly white male, property-owning electorate through newspapers. In the earliest presidential elections, it was considered unseemly for politicians to tout themselves in public. No longer.

(Photo by Justin Sullivan/Getty Images)

In the age of super PACs and mega donors, candidates routinely charter flights across the country to get to and from big fundraisers -- but the bus is the standard bearer. Romney campaign buses have worn slogans such as "Conservative, Businessman, Leader" and "Every Town Counts." The Romney campaign bus, above, with its candidate in Tarlton, OH, at times does not even have the former governor on it, and will instead transport local politicians to rallies, or go on missions to taunt Obama supporters.

(Photo by White House Photographer Pete Souza)

President Obama, pictured here leaving Ireland in 2011, has to use Air Force One to travel by air, whether it’s official state business or part of his campaign trail. The president is supposed to reimburse taxpayers when the plane is being used for travel to fundraising events or stump speeches. One watchdog organization estimates that it costs over $180,000 an hour to operate Air Force One.

(Puck magazine, collected by Library of Congress http://www.loc.gov/pictures/item/91482121/)

The grassroots-style campaign for president became tradition by the time of Reconstruction, but, arguably, the first candidate to turn it into a national phenomenon was the populist Democratic nominee of 1896, William Jennings Bryan. Bryan conducted a six-week "whistle-stop" tour leading up to the election, usually giving 20 to 30 speeches a day.

Photo via Truman Presidential Library. (link: http://bit.ly/RkfR55)

Before Air Force One, there was U.S. Car No. 1. The Ferdinand Magellan was specially armored to carry President Franklin Delano Roosevelt during World War II. Harry Truman used the Magellan for his famous whistle-stop campaign during the 1948 election. One of the most famous moments of campaign history: Truman stood on the Magellan's observation platform, newspaper triumphantly hoisted high, holding the famously incorrect headline, “Dewey defeats Truman.”

(Photo by News bureau of United Air Lines-United Air Lines)

President Eisenhower was considered all but a lock for re-election in 1956, but at the Republican convention that year, a delegate wrote in “Joe Smith" for Vice President to protest the unanimity of the GOP nominations. Here, Democratic opponent Adlai Stevenson meets a Chicago supporter named Joe Smith before embarking on a tour of speeches with his campaign plane, the Joe Smith Express.

(Photo by Paul J. Richards/AFP/Getty Images)

With more campaign cash to go around, focus on the presidential primaries has grown over time. Coach buses allow candidates to travel to many destinations in one state, and have room for the media to come along for the ride. John McCain’s “Straight Talk Express” had a welcoming reputation among the press corps during his 2000 primary run.

Photo via Reagan Presidential Library

The Eisenhower administration retired the The Ferdinand Magellan due to lack of use in 1958. But it made a comeback in 1984 when President Reagan used it for one-day trip in Ohio. Campaigns have since brought back the nostalgic whistle-stop style, including President Obama in 2008 when the Illinois Senator campaigned on a restored Pullman car. McCain, who opposed Amtrak funding, carried on whistle-stopless.

FDR loved traveling by rail. He even had his own entryway to Grand Central Terminal in NYC, where a car specially designed for him* still sits, entombed and dusty, below the active station as we reported in our story on the lost subways of NYC. See pic here.

*An earlier version of this sentence incorrectly referred to this car as the Ferdinand Magellan.