J.J. Cale, a quietly influential singer-songwriter who stayed in the background while better-known musicians had hits with his songs, including “After Midnight,” “Cocaine” and “Call Me the Breeze,” died July 26 at a hospital in La Jolla, Calif. He was 74.

He had a heart attack, his manager, Mike Kappus, told the Associated Press.

Mr. Cale was never as well known as Eric Clapton, Lynyrd Skynyrd, Johnny Cash or many of the other musicians who recorded his songs. But if his career was unsung, his songs were not.

He had been a working musician since the mid-1950s but was struggling — “dirt poor,” as he put it — and about to quit when he was driving through Tulsa in 1970 and heard Clapton singing “After Midnight” on the radio.

The song, which Mr. Cale had written in about 1966, made the Billboard Top 20 and was Clapton’s first major hit as a solo artist. It also secured Mr. Cale’s musical and financial future.

 Singer-songwriter J.J. Cale plays during the Eric Clapton Crossroads Guitar Festival in Dallas, Texas. Cale, whose best-known songs became hits for Eric Clapton with ’After Midnight’ and Lynyrd Skynyrd with ’Call Me the Breeze,’ has died. He was 74. (Tony Gutierrez/AP)

“I went, ‘Oh, man, I might stay with the music business,’ ” Mr. Cale told the Los Angeles Times in 2009. “I was about ready to get out of it. I was playing Friday and Saturday nights and looking for a day job.”

Mr. Cale won a Grammy Award for best contemporary blues album for “The Road to Escondido,” a recording he made in 2006 with Clapton, but for years he was content to live in obscurity and let his understated songs speak for themselves.

“In my humble opinion,” Clapton wrote about Mr. Cale in his 2007 autobiography, “he is one of the most important artists in the history of rock, quietly representing the greatest asset his country has ever had.”

Mr. Cale and his fellow Oklahoman Leon Russell were credited with developing the “Tulsa sound,” a relaxed style of bluesy country rock with minor chords, simple lyrics and a shuffling beat that helped define a decade of roots-based, Southern-style rock-and-roll.

Mr. Cale’s “Call Me the Breeze,” which was recorded in 1974 by Lynyrd Skynyrd and later by the Allman Brothers and Cash, became a classic guitar-driven anthem to the open highway: “Well, now they call me the breeze / I keep blowin’ down the road.”

Clapton played “After Midnight” in his concerts for decades, along with another tune by Mr. Cale, “Cocaine,” which was first recorded by Clapton in 1977. Often considered a paean to drug use, the song could also be interpreted as a wry, unflattering description of it: “If you wanna get down, down on the ground — cocaine.”

Neil Young, Mark Knopfler, Bryan Ferry and Clapton all cited Mr. Cale as an influence, and critic Geoffrey Himes wrote in The Washington Post in 1983 that Mr. Cale’s “superb guitar leads — which other guitarists study faithfully — are so thoroughly woven into the fabric that one has to mentally unravel the songs to identify what miracles Cale is working.”

Other well-known performers who recorded his songs include Carlos Santana (“The Sensitive Kind”); Cissy Houston (“Cajun Moon”); Captain Beefheart and Bobby “Blue” Bland (“I Got the Same Old Blues”); Chet Atkins and Jerry Garcia (“After Midnight”); and Tom Petty (“I’d Like to Love You, Baby”).

“I’ve never sold a lot of records,” Mr. Cale told the San Diego Union-Tribune in 1990. “My music’s gotten much more famous than me.”

John Weldon Cale was born on Dec. 5, 1938, in Oklahoma City and grew up in Tulsa. He was playing guitar in Western swing and rock-and-roll bands by the mid-1950s and often worked in Tulsa with Russell, who became an influential songwriter and pianist.

By 1964, Mr. Cale had moved to California and began to master studio work, as well as the guitar and other instruments. He changed his stage name from Johnny Cale to J.J. Cale, to distinguish himself from John Cale, who played in the Velvet Underground with Lou Reed.

Mr. Cale recorded his first album, “Naturally,” in 1971, and his only significant hit as a performer, “Crazy Mama,” came out in 1972.

Mr. Cale was considered a reclusive enigma because his records seldom had his picture on them and because he rarely went on extensive tours. He lived for years in a rural area outside San Diego without a telephone. Survivors include his wife of 16 years, Christine Lakeland, a musician who often played in his bands.

Mr. Cale’s musical style changed little over the years, with subtle finger-picking on guitar, backed up by quiet vocals — what he called “front-porch noodling.”

“There are entertainers and there are musicians,” Mr. Cale said in 1988, “and I never was an entertainer.”