Contrary to popular opinion, the USO (United Service Organization) wasn't entirely about WWII-era dances and popular entertainment. Formed in 1941, it was established as a private non-profit organization devoted to providing morale-building services of all kinds to members of the armed forces. This included religious needs, games and recreation, temporary lodging, postage services, the distribution of books and magazines, and food stations in cities, ports and railway stations. Particularly famous were USO doughnuts. If USO volunteers were handing out food, doughnuts were sure to be involved!
The USO was chartered by Congress to bring a variety of hitherto separate units under one united banner, but it was and remains technically independent of the US government. I say "technically" because the USO worked very closely in conjunction with the War Department, and continues to coordinate its efforts today with the Department of Defense and Homeland Security. No matter how nominally independent, the organizers of USO events and services were never going to put their people in harm's way or compromise military operations.
USO dances became a staple of life of wartime life. Girls considered to be of the best character were chosen to host and participate in these canteen dances, both at home and in foreign nations such as Britain. Morale was buoyed by the girls' clean-washed hair, pretty smiles, and patient conversations. Because of how near this skirted toward hints of offering their bodies of comfort--eep! almost prostitution!--the USO was especially strict to enforce their chosen boundaries of propriety.
Girls were trained in how to talk with servicemen, how to make them feel included, and how to firmly tell them "no" at the end of the night. Volunteers were discouraged from dancing too frequently with the same man, and they were forbidden from leaving the premises with servicemen. Even the exchange of phone numbers so that eager young people could arrange an after-work rendezvous was prohibited. (Not to say some folks didn't get around the restrictions!)
Camp Shows also became widely recognized aspects of USO morale. Entertainers from all walks--from Bob Hope and other tremendous stars, to independent troupes of acrobats, singers, poets, classical musicians, and ballerinas--all made the rounds. Homefront shows were organized to keep restless men in training camps from becoming too bored and destructive to local towns. "Foxhole Circuit" tours of the the European and Pacific Theaters soon followed, from Alaska to Egypt to New Guinea. These intrepid performers traveled at their own risk, but they also performed under the USO's very strict watch. Anyone who deviated from an approved show schedule and script could be sent home instantly, contract canceled.
Contrary to what you might expect of entertainment aimed at hundreds of hard-up, lonely soldiers, USO performers were expressly forbidden from making their shows too vulgar or sexual. In fact, the longer a man had been in the field--such as Marines who had not been home for two years or more--the more eager he was for wholesome entertainment. They had seen enough vulgarity and had experienced far too much degradation and shame to want that reflected in their entertainment. Pretty girls in good Sunday dresses who sang songs of home were the most appreciated entertainers--the sorts of girls they were fighting for, the sort of girls waiting for them to return.