Which Motown song became the label's first Billboard Hot 100 number-one single?

The Motown song that became the label’s first Billboard Hot 100 number-one single was “Please Mr. Postman.”

The 1961 hit was recorded and released by the Marvelettes, a girl group signed to Motown’s Tamla label. It was issued as a single in August 1961 and reached number one on the Billboard Hot 100 in December. The song also topped the R&B chart, becoming Motown’s second million-selling record and its first major number-one pop hit.

The writing credit is shared by Georgia Dobbins, William Garrett, Freddie Gorman, Brian Holland, and Robert Bateman. Its backing musicians included members of the Funk Brothers, Motown’s celebrated studio ensemble. The success of the record helped establish the Marvelettes as an important early Motown act, even though later releases did not match the impact of their debut.

A frequent source of confusion is the later version by the Carpenters, which also reached number one on the Hot 100 in 1975. The question refers to Motown’s original recording, not that cover. The Beatles also recorded the song in 1963, adding another familiar version.