Going way back–and by that I mean to the late 1920’s (in the early days of Louis Armstrong)–there were the Boswell Sisters. The Boswell Sisters, a trio with Connee, the lead, wheelchair bound, sang in close, intricate, twisting harmonies. They had a luster of being, or sounding, Southern. Also of note, is that Connee sang on records in duo with Bing Crosby.
Following the Boswell Sisters in the 1930’s came the Andrews Sisters, Patty, Maxene and LaVerne. They had many major hit records, both with Bing Crosby, and by themselves. In the former category, most outstanding is the lovely Cole Porter song, Don’t Fence Me In. The Andrews Sisters’ greatest hits, by themselves, were the poignant, wartime, I’ll Be with You in Apple Blossom Time, and the jump, upbeat , Boogie Woogie Bugle Boy (of Company B.) But to me their greatest recording was Bie Mir Bist Du Shoen, lovely, upbeat close harmonies among the three sisters, and was an expression of how appealing the admired one is. Finally, all of these Andrews Sisters records from the 1930’s and 40’s, were on Decca records.
The Andrews still were having major hits into 1950. The plaintive, I Can Dream, Can’t I?, then, was their last big hit, and the spigot shut off, for them, thereafter, though singing partner, Bing Crosby, continued as a major source of hits into 1951.
During this period, (after the Andrews Sisters), the most important girl group was the Chordettes. With Archie Bleyer (Cadence records), one-time band leader for Arthur Godfrey, the Chordettes, a close harmony group, had their only number one hit record, Mr. Sandman. They also, later, had a hit with Lollipop.
Another major girl group during this period was the Fontane Sisters, once back-up singers for Perry Como. Rock Love, and later, Hearts of Stone, RCA records, were their big hits.
The McGuire Sisters, Coral records, had two large hits, with Goodnight, Sweetheart, Goodnight, and Muskrat Ramble. I thought their sound was rougher, and not as appealing, as any of the other girl groups during this period.
The DeCastro Sisters had one big hit, Teach Me Tonight, Abbott records. I could imagine their having to sing this song thousands of times, post-hit, and becoming thoroughly sick of doing it.
The one other major hit record was rollicking, No More, the DeJohn Sisters, Epic records.
It needs to be noted that during this period, 1950-1954, when multi-tracking came into vogue, the two greatest exemplars were Patti Page (Mercury records), and, with Les Paul, Mary Ford (Capitol records.) In a strange way, their multi-tracks make them girl groups of their own, in this period.
Finally, notably, there were more sister groups among the girls, proportionally, than brother groups, among the boys (or, if preferred, women and men.)
These , then were the major happenings, as I recall, in this category, during this period.