However, much of the label's success has already been consigned to the record books. Most of its Detroit-based stable of stars from the 1960s and early 1970s - Michael Jackson, the Supremes, Marvin Gaye, Smokey Robinson, Gladys Knight - have either passed away or moved on to competing labels. Of its best-known artists, only Stevie Wonder has never left Motown.
Only recently has it begun to recapture some of its edge after losing touch with the black stars - Prince, Whitney Houston, Jody Whatley, Janet Jackson - who came of age in the 1980s.
But Polygram is buying what may be the most valuable single pop-music catalogue anywhere. This demonstrates the enduring popularity of 'the Motown sound'- the signature quality of its founder, Berry Gordy.
The one-time boxer and automobile assembly plant worker is now the 'Howard Hughes of black America', a multi-millionaire living in a mansion in the Los Angeles neighbourhood of Bel Air. He travels in disguise and is always flanked by bodyguards.
But he began operations in 1959 in a much more modest style - a makeshift recording studio set up with dollars 700 borrowed from his family. Thanks largely to his ear for talent and rigorous production standards, Motown's ratio of hits to singles recorded in the 1960s was the highest in the industry, if not in history.
Mr Gordy was also a brilliant marketer. In an era of 'payola', when richer white studios used cash incentives to guarantee radio airtime for their new releases, he offered black disc-jockeys access to his acts for free. For example, they could book the Supremes at a local venue for a weekend in exchange for playing their latest single.
In his few public statements, Mr Gordy projected himself as a non-threatening symbol of black capitalism, but he was also prepared to appeal to racial solidarity to get his records preferential treatment, at a time of heightened black-white tensions in the US.
'He was an executive who used his blackness as a weapon as shrewdly as any civil rights leaders,' said Nelson George, black music critic for the US industry magazine, Billboard, and author of the definitive book on Motown, Where Did Our Love Go?
However, Mr Gordy's commercial success came 'by tailoring black rhythm and blues to the tastes of an open-minded generation of white American teenagers', argues Robert Christgau, the veteran music critic for New York's Village Voice newspaper.
In the early 1970s, competitors finally began to appreciate the money-making potential of black music, repeatedly offering to buy him out and eventually raiding his producers, writers and artists. CBS signed Sly & The Family Stone and Santana in 1971; by 1980, it had 125 black acts under contract. Marvin Gaye also went to CBS; Diana Ross was lured away by RCA.
But the money offered by the big labels wasn't the main reason artists defected. Many complained of mistreatment by Mr Gordy; he reportedly slapped a reluctant Marvin Gaye around backstage to get him to perform, and was loath to share Motown's wealth with the artists he discovered.
'If it weren't for the acts, there wouldn't be any Motown,' Gladys Knight told one reporter a decade ago after deciding not to participate in the label's 25th anniversary celebration. 'Or Mr Gordy, for that matter.'
He brushed aside the criticism, as well as increasingly frequent suggestions in the 1980s that Motown was losing momentum. He promised new projects right up until 1988, when he sold the label for dollars 61m to MCA and Diana Ross's Boston Ventures, retaining only the publishing rights to Motown's old songs for his Jobete Music Company. That also proved to be a clever transaction, allowing him to profit from the demand for Motown classics that will accompany Polygram's marketing efforts. Before last week's sale, Jobete's value was estimated at between dollars 100m and dollars 200m, and many industry experts thought it might be worth at least as much as Motown.
Last week, Mr Gordy remained ebullient, saying through a spokesman: 'I feel a great deal of pride today about Motown's heritage and what is to come.'
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