President Obama will travel to South Dakota on Friday. (AP Photo/Mike Stewart)

President Obama's visit to South Dakota Friday means he'll be able to strike a major item from his bucket list: visiting all 50 states while in office.

The president will travel to Watertown, South Dakota Friday to deliver the commencement address at the Lake Area Technical Institute. And with that visit, he joins a rare club of presidents who have made it to every state in the Union while in office. The others: Richard Nixon, George H.W. Bush and Bill Clinton. (Bush's spot in the club is particularly notable since he accomplished the feat before the end of his first and only term.)

Obama, who had yet to visit four states at the beginning of the year, has steadily been checking them off -- Idaho in January, South Carolina in March and Utah in April. That travel has been part of an expressed goal by the president himself to make it to all 50 states before he exits the White House in January of 2017.

[Obama aspires to visit all 50 states as president.]

(As my colleague Colby Itkowitz points out, Obama has visited all 50 states already -- but that tally includes states he visited as a candidate and not as president.)

The White House is already taking something of a victory lap to commemorate the accomplishment: Pete Souza, the White House's chief official photographer, on Thursday published a photo gallery on Medium featuring one picture from each state visited to date.

The politics of visiting all 50 states is hard to resist analyzing: all four of the final states that were left on his list are deep, deep red and didn't vote for him in either 2008 or 2012. Last year, Gallup tracked the president's average approval rating in South Dakota at just 32 percent, with 62 percent disapproving. His supporters will be quick to point out he's visiting them anyway.

(Here it's also worth remembering that former president George W. Bush notably visited every single state before leaving the White House except Vermont, incidentally home to a heavy -- if symbolic -- push to impeach him.)

South Dakota Sen. John Thune, a Republican, welcomed Obama's visit to the Mount Rushmore State and doesn't seem at all bitter about it being last: "The president has clearly saved the best for last, and we welcome him to our great state,” Thune said.