Think of Philadelphia and besides gooey orange cheese oozing over an iconic sandwich and the country's most notorious sports fans, what comes to mind at least on the cultural side of Pennsylvania's largest city—and the onetime capital of the USA—is the music of Philadelphia International Records. Smoother than the gritty Memphis soul of Stax or Hi Records, less risk averse and more album-oriented than Barry Gordy's Motown pop, sexy, sweeping Philly soul was ultimately highly influential Black Music.

One of the main sources for what became disco, Philadelphia International Records (celebrating its 50th anniversary in 2021), was the brainchild of a pair of session musicians turned songwriters and empire builders—Kenneth Gamble and Leon Huff. The duo not only signed the acts and ran the business, but also wrote and produced much of the music. An early partnership with songwriter, arranger and producer Thom Bell was also key. Though PIR's lifespan was short—from its founding in 1971 until Gamble and Huff wound down their operations in the mid 1980s—its superpowers were an incredible songwriting streak by Gamble and Huff (they eventually wrote over 3,000 songs) and the wisdom to match the right material with the right player. Drawing on a deep pool of pre-existing Philly musical talent, PIR's arrangements are nothing short of extraordinary, filled with dramatic string sections, a get-down, four-on-the-floor beat and tasty details like horns and vibes in just the right places. It was classy, smoothly produced dance music that alternated between the pain of lost love and the joys of the flesh to message songs of compassion and commitment, human kindness, or greed and perhaps, in the end, a better future for all.

PIR had two other fundamental advantages. Engineer Joe Tarsia's Sigma Sound Studio, the second East Coast studio to have 24-track recording (after RCA), was located blocks from the PIR headquarters on Broad Street in downtown Philadelphia; Tarsia, credited with coining "black music in a tuxedo" about PIR, liked to hear the room in recording sessions. Then there was the Sigma house ensemble—the thirty-plus member MFSB, consummate pros for whom grooves were instinctive. MFSB (Mother Father Sister Brother) counted among its outstanding instrumentalists bassist Ronnie Baker, conguero Larry Washington, drummer Earl Young, guitarists Bobby Eli, Roland Chambers and Norman Harris, organist Lenny Pakula and vibes player Vince Montana.

As a musical preface to the PIR story, two recordings deserve special mention. "Expressway to Your Heart" by The Soul Survivors (released in 1968 on Philly-based Crimson Record), was the first hit single produced by the team of Gamble and Huff. The other, The Intruders' immortal slice of smooth soul, "Cowboys to Girls," a pre-PIR single written by Gamble and Huff and released on Gamble Records to national acclaim set the template for the coming PIR sound: punchy brass, multi-part vocal arrangements and elaborate string backing.