The 69-year-old actress, daughter Lisa Marie Presley and thousands of fans gathered outside the late singer's home in Memphis to mark the occasion. Shelby County mayor Mark H. Luttrell Jr. proclaimed the date Elvis Presley Day, and the Graceland website live-streamed the festivities.
"Where did the time go?" Presley mused earlier in an interview with Today. "It's hard to believe, 80 years old. It makes you realize how young he was when he passed, which was only 42 ... I felt that he still had so much he wanted to do."
The birthday celebration kicked off four days of charity, music and movie events at Graceland. The home remains a major tourist attraction, and a new website dedicated to the singer's music launched Thursday morning.
"I think definitely music would always be in his life," the actress reflected of her ex-husband. "He loved it, it was in his blood. It was born to be who he was, truly, and he enjoyed being who he was. I think that to continue his music was something he would do [if he had lived]."
Elvis Presley was born in Tupelo, Miss., on Jan. 8, 1935. He and Presley married in May 1967, and had one child together, daughter Lisa Marie, before they divorced in October 1973. The singer died of a heart attack at age 42 on August 16, 1977.