Per his son Billy, Mack's passing was due to "COVID-19 with underlying conditions."
Mack wrote "Blue" and first recorded it for Starday Records in 1958. Billboard described it as "a slow-tempo, relaxed item, with Mack's vocal backed by instrumentation featuring a honky tonk type piano. A flavorsome side."
"Blue" was recorded a handful of times (Kenny Roberts in 1966, Roy Drusky circa 1960-70s, Polly Stephens Exley in the late 1980s and Kathryn Pitt in 1993) before 13-year-old Rimes secured its place in country music history with her 1996 version. Rimes' version earned Mack two coveted prizes: a 1996 Grammy Award for Best Country Song and a 1996 Academy of Country Music Award for Song of the Year.
Mack denies rumors that he wrote the slow-tempo song with Patsy Cline in mind. Instead, he tells a much more straightforward story that makes the song sound like a happy accident.
"I wrote "Blue" while picking my new guitar in my home in Wichita Falls, Texas," he wrote for Trucker's Connection in 2013. "I was creating some note changes on the guitar when the song entered my mind. Although I wasn't watching the clock, the melody and lyrics came to me in a completed form within 15 minutes. My wife at the time said, "That's the best song I've ever heard! You need to record it as soon as you can!"
His other successful song, "Drinking Champagne," was a surefire hit for Cal Smith and George Strait.
For truck drivers and Texans, Mack is just as well known as the host of The Country Roads Show (later known as the U.S. 1 Trucking Show and the Midnight Cowboy Trucking Show). These overnight country radio broadcasts on Fort Worth's WBAP could be heard far and wide by truckers.
Mack later worked for SiriusXM.
For more on Mack's legacy, check out his memoir, Bill Mack's Memories from the Trenches of Broadcasting.