"The Door is Always Open" brought the mixed-gender trio its inaugural country chart-topper.

Dave & Sugar circa 1977.

Michael Ochs Archives

He was once a member of the Grand Ole Opry quartet The Four Guys, but he made his mark in country music as the sole guy in a group with two women.

Dave Rowland’s trio, Dave & Sugar, launched in April 1975 as an opening act for Charley Pride, with Jackie Frantz and Vicki Hackeman as Rowland’s original female singers. “The Door Is Always Open,” the trio’s second single, took the act to No. 1 on Billboard’s Hot Country Songs a year later, on the list dated July 10, 1976.