The 244-year-old letter, donated by Dallas oil company owner Barron U. Kidd, condemns the killing of three American Indians by white settlers, the Austin (Texas) American-Statesman reported Wednesday.
"It seems this murder (for it deserves no other name) was committed on light provocation, upon three Indians of the Mingo Tribe," Washington wrote to John Armstrong, a justice of the peace and land surveyor who advised Washington on land dealings.
The letter will go to UT's Dolph Briscoe Center for American History.
"It's in great shape," said Don Carleton, the center's director. "It's not just of research value for people interested in Washington. For someone studying the history of American Indians in the colonial period, that's a very important letter."
Kidd, a UT graduate, said he enjoyed his time at the university and want to give something back.
"The Briscoe Center is a vital and growing institution," Kidd said. "They did not have a Washington letter. I thought a letter from the father of our country makes sense. I'm pleased to have given it."