Peek was found dead in his bed by his wife. An autopsy has been scheduled to determine the cause of death.
"America's" most famous songs include "Tin Man", "Sister Golden Hair", "Daisy Jane", and "Lonely People".
Peek left the band in 1977 and became a Contemporary Christian Music artist.
He was 60.
UPDATE: The St. Francis County Coroner says Peek died from severe heart disease and an enlarged heart.