He was 79 years old.
Just last week, he canceled the rest of the shows he had slated for this year.
Born on April 6, 1937, Haggards early life was like an American myth.

Credit: Paul Natkin/Getty Images
At nine-years-old, Haggards father died of a brain tumor.
Later, he quit school.
Among those characters were gypsies, farmers, blue-collar workers, widows, musicians, and alcoholics.
His catalogue offers some of the most richly textured, vividly rendered country songs in history.
In 1957 at age 20, Haggard was arrested for breaking and entering a local roadhouse.
(Cash would record his famed San Quentin album there nine years later.)
Haggard credits music as what saved him from continuing a life of crime.
Shortly after his parole in 1960, he began playing lead guitar in a local Bakersfield country band.
Cash and Haggard would remain close friends until Cashs death in September of 2003.
In that plot-gone-wrong, Hendricks killed a state trooper while fleeing and was put to death.
Career-wise, Haggard, who pioneered the Bakersfield Sound, released his first single in 1963.
It sold 200 copies.
His third landed him a record deal with Capitol.
Every year, between 1966 and 1987, he had at least one Top Five country hit.
In total, he notched 38 No.
1 country songs and released more than 65 albums.
Perhaps Haggards most enduring tune was Okie From Muskogee.
Haggard had plenty of industry accolades, too.
In 1994, he was inducted into the Country Music Hall of Fame in 1994.
A longtime critic of the Nashville music business, Haggards acceptance speech began, Ive had 30 days notice.
Ive had notices for evictions.
In 2010, Haggard received the Kennedy Center Award for lifetime achievement and his outstanding contribution to American culture.
In his later years, Haggards music focused heavily on his perceived decline of America.
She said, I can in one word: Unpredictable.
He continued, I come by it honestly but I also plan it.
And I wont worry about the next show until I get on stage.
He was married to Lane from 1993 until his death.