here is a Fred Waring and the Pennsylvanians Christmas song
Clearly, this is "popular" rather than traditional or sacred Christmas music, but songs like these made their way into Christmas variety albums that people might play while hosting a holiday-themed party during December. A note about US society that may seem odd to Europeans: people often entertain at "holiday parties" (complete with Christmas decorations, Christmas food specialties, and Christmas music) on the first, second, third, and sometimes fourth weekends of Advent (more common on the 4th weekend if it is a full week before Christmas, less common if it is shortly before Christmas). The tree is up and decorated. Having been a guest in European homes in early December, normally there are no Christmas decorations until Christmas Eve. One might see an Advent wreath, or possibly some green decorations (poinsettia, holly, etc.) but no tree or actual Christmas decorations until shortly before Christmas.
This is in keeping with the tradition of Advent being a pentitential time, when lavish celebrations are inappropriate until Christmas, even among people who do not attend church and who are not particularly religious. Meanwhile, in the USA, you see nearly everyone, whether religious or not, participating in holiday parties (the "office" party and usually friends having parties, typically on Fridays, Saturdays, and Sundays). Liturgically, mainly Catholics, Anglicans, and mainstream Protestants (Methodist, Lutheran, Presbyterian) observe Advent at church, whereas nondenominational and evangelical Christians barely known what Advent is. But it doesn't matter: nearly everyone attends a holiday party or two.
Churches that observe Advent here taking varying approaches to how strictly they observe Advent. Most Catholic and Anglican churches, for example, would not host any "Christmas concerts" (the idea being that if you want to hear Christmas carols, you can come to Christmas Eve services and hear them). More common would be musical presentations that are loosely related to Christmas (e.g. Handel's Messiah) but not "Christmas per se". Another example would be the "Ceremony of Lessons and Carols" in some Anglican churches: the carols relate to Advent more than to Christmas, and the Bible readings are likewise Advent-related. On the other hand, I've attended a Christmas concert at a local Presbyterian church which was fully decorated for Christmas two weeks early and Christmas carols were sung. I've also sung in a Messiah concert in a Methodist church in early December which was already fully decorated for Christmas, three weeks early.
