To have an affair with a woman/multiple women, preferably from Argentina. Email is the main form of communication, although in this case, an actual visit is needed.
Press: Where is Sanford?

Joel Sawyer, Sanford's spokesperson: Uhh...He's... Hiking the Appalachian Trail...Yeah, that's the ticket.
by kneenuh July 13, 2009
For a man to have vaginal sex with a woman who is not his wife. Can be used as a reference to a married man having an illicit sexual affair, and deceiving everyone about it by telling them he's doing something else.

"The Appalachian Trail" refers to the woman's vagina.

Mark Sanford, the Governor of South Carolina, flew to South America to see his mistress and told everyone, including his staff, that he 'would be gone for a few days hiking the Appalachian Trail.'
"Does Bob's wife know he's taking that hot secretary with him on his business trip? Looks to me like he's planning on hiking the Appalachian Trail."
by impulsiveone July 16, 2009
Any cover story a politician or other person of power uses when cheating on that person's spouse.

From the disappearance of Gov. Mark Sanford in 2009.
What happened to the senator this weekend?

He's off hiking the Appalachian Trail *wink*
by Colby B. June 24, 2009
Euphemism for leaving the governor's mansion, without telling anyone where you're going, and then disappearing for a week while breaking up with your mistress in Argentina.
A: Where's Mark, his security detail and wife are wondering? B: Oh he's out Hiking the Appalachian Trail.
A: I hope he's wearing a condom.
by Schnyper June 24, 2009
Cheating on your wife with some Argentine hussy sexpot.
Gov. Sanders of South Carolina was Hiking the Appalachian Trail on Father's Day instead of hanging out with his family.
by djnonsequitur June 24, 2009
Euphemism for sticking it in the butt of an Argentinian woman.
Governor Sanford (R) was furiously hiking the Appalachian Trail for several days over Father's Day weekend.
by ZezAzeZ June 24, 2009
To have an extramarital affair in another country, especially South America.
South Carolina Governor Mark Sanford was hiking the Appalachian Trail last week and didn't tell anyone where he was, but he's really really sorry about it.
by Ken Starr June 24, 2009