When President Obama visited the Standing Rock Sioux Tribe in Cannon Ball, North Dakota, on Friday, he marked another state off his list. As president, he has now traveled to 46 of the 50 states.
Which ones are still waiting for a visit from President Obama?
Idaho, South Carolina, South Dakota and Utah.
Obama lost all of those states by a significant margin in 2012. They vote solidly Republican. And, it turns out, with the exception of South Carolina, they aren't popular destinations for other presidents either.
"They are scarcely populated," says Brendan Doherty, an associate professor of political science at the United States Naval Academy who has built a database of presidential travel and events going back to the Carter presidency. "They are electorally non-competitive and they tend to vote for Republicans in presidential elections. And they're also distant from Washington, D.C. They tend to be hard to get to."
According to Doherty, the states presidents visited least since 1977 are: Vermont, North Dakota, Idaho, Montana, and Rhode Island.
Doherty writes about presidential travel patterns in his book "The Rise of the President's Permanent Campaign." As you might guess from the title, his analysis is oft-neglected states miss out on Air Force One landings in part because presidents from both political parties don't have much to gain electorally from visiting.
Doherty explains that of the past six presidents, only one, George H.W. Bush, visited all 50 states in a single term. And he lost his bid for re-election.
Some say he should have spent more time focused on pivotal swing states (not to mention the economy). Presidents tend to spend a lot of time in swing states in their first terms and then, in their second term, visit the states with less electoral heft.
"Presidents would like to visit all of the 50 states they lead, but time is scarce," says Doherty.
When it comes to Vermont (currently ranked 49th in population), it often seems time is too scarce: Carter, Reagan and George W. Bush never made it there. George H.W. Bush, Clinton, and Obama have all been there just once as president.
It Takes a Disaster
Before early May, President Obama hadn't stepped foot in Arkansas, either as a candidate or as president. The tornado that ripped through Faulkner County and the communities of Mayflower and Vilonia changed that.
Obama lost Faulkner County by more than 30 percentage points in 2012, which is to say he's not a popular political figure there. And that made his visit an uncommon one: he spends much of his time in places where he won the popular vote.
As for Mississippi, it can thank the Gulf of Mexico oil spill in 2010 for its only visit from President Obama. In Alabama and Oklahoma, deadly tornadoes brought Obama back to those states for second visits.