"I think of those who will serve on this ship and those who will see it in different parts of the world. And perhaps they, too, will come to know who Medgar Evers was and what he stood for," Myrlie Evers-Williams said at Jackson State University, where Mabus made the announcement.
Evers was Mississippi field secretary of the National Association for the Advancement of Colored People when he was assassinated outside his Jackson home on June 12, 1963. He was 37.
"He gave his life for his country," Mabus told an audience of about 200.
Mabus embraced Evers-Williams and Medgar Evers' brother, Charles Evers, as they stood before a screen with a color likeness of the ship and a black-and-white photograph of Medgar Evers.
The USNS Medgar Evers will be built at General Dynamics NASSCO in San Diego, and Mabus said construction of the 689-foot vessel would take up to two years. The ship will deliver food, ammunition and parts to other ships at sea.
During the 1950s and early 1960s, Medgar Evers organized nonviolent protests, voter registration drives and boycotts in his home state.
Mabus was a 14-year-old living in northern Mississippi when Medgar Evers was killed, then served as governor from January 1988 to January 1992. He said he chose to name his first Navy ship after Medgar Evers because he was a pioneer.
"He was committed to his fellow human beings and the dream of making America a nation for all its citizens," Mabus said.
Medgar Evers was born in tiny Decatur, Miss., about 60 miles east of Jackson. He served in the U.S. Army during World War II, fighting in France. After he returned to Mississippi, he earned a degree from what is now Alcorn State University and became involved in the burgeoning civil-rights movement.
Medgar Evers' assassination prompted President John F. Kennedy to ask Congress for a comprehensive civil rights bill.
Evers is buried in Arlington National Cemetery. It was 1994 before his killer, white supremacist Byron De La Beckwith, was convicted of murder.
Evers-Williams _ who lives in Los Angeles and Bend, Ore. _ thanked Mabus for fulfilling a promise he made to her more than 20 years ago, that he'd find an appropriate way to commemorate her late husband's legacy.
She said she flew to Mississippi for Friday's ceremony without knowing why she had to be there. She joked that Navy officials and her friends in Mississippi who arranged the trip did a good job of keeping the information from her.
"Mission accomplished," she told Mabus with a smile.
Associated Press Writer Philip Elliott contributed to this report from Washington.