After the 2008 presidential caucus, Iowa State University’s David Swenson crunched the numbers on all the campaign spending for the final two quarters of 2007, presumably the point when candidates start gearing up for Iowa’s early January ballot. During those six months, candidates spent just $15.5 million in the Hawkeye State. Combined spending in Iowa and New Hampshire — which follows Iowa with a first-in-the-nation primary -- amounted to a paltry 7.7 percent of campaign spending by both political parties, totaling just over $352 million.

Granted, candidates did spend more in Iowa than they likely would have if the state did not have its early caucus. Despite being the 30th-most populous state in the country, Iowa hosted the campaign’s seventh-biggest spends in late 2007.

Why don’t presidential campaigns spend more in Iowa? As Swenson explains, a lot of the early work on a campaign isn’t about going door-to-door in Des Moines. It’s hiring consultants, testing out messages and doing work inside the Beltway, rather than in the Midwest:

Candidates create exploratory committees to test the waters. They engage first in fundraising. Candidates raise money where there is money. Comparatively speaking that is not Iowa or New Hampshire. Candidates require election specialists to assist them. Those specialists, veterans from other campaigns mostly, will reside in major cities or in and around the Washington, D.C., area. In consequence, we would expect higher levels of organizational spending in the states of Virginia, Maryland, the District of Columbia, and, to lesser degrees, Pennsylvania and New York. We would also expect more spending in the home states of the candidates as the candidates will all tap into the professional network that helped get them elected to statewide or federal office.

(h/t: Planet Money)