Let me go out on a limb and take a stab at some generalities.

Most of what popular music history tells has to do with public performance venues such as the music hall, the musical stage and vaudeville, before these were driven out by acoustic recording (1890s-1920s), radio (1920s onward), then electrical recordings, and eventually the electronic media that blanket us today.

Sadly there is relatively little hard detail on what music in the average home was like, how it sounded, what it was played on, what the singing styles were, etc. etc. Vogues in upper middle-class to upper-class homes for the spinet, piano, virginals and guitar, among other instruments, have been noted, and rather elegant, mannered performance styles apparently prevailed, as compared to the more casual "natural" singing styles made popular after about 1920.

The masses, however, did music very differently. By contrast with the well-to-do, the poor performed on what they could afford: cheap violins, button accordions, the occasional banjo, slide whistle or fife, harmonica, even homemade instruments such as drums. Sears Roebuck and Montgomery Ward cheap instruments led to a huge boom in banjo and guitar playing once these became available in the late 19th century, but before that, virtually all instruments were custom-made, scarce, and expensive.

Most often the lower classes sang unaccompanied -- both because instruments cost money they didn't have, and because they had inherited a vital tradition of unaccompanied singing stretching back centuries. A capella was their normal way of singing not just traditional songs, but such popular songs, novelties, hymns, etc. as came their way.

All this is common knowledge. But it is based on fragile, incomplete information. For example, there are few detailed written first-person accounts of what music made in the home actually was like for populations in different parts of urban and rural America --

-- or any other country for that matter, except possibly some European countries where, dominated by long-standing conservatory-style approaches, classical music and classical-styled arrangements were far more integrated into the general population. In America what made the difference was relatively less intensive, less far-reaching music education for the general population before, say, 1900, which allowed Americans to remain freer and more individualized in their way of making music for themselves in private.

Sources worth checking: Among the few who have really gone into some depth about the history of American popular music is Sigmund Spaeth.

His books, if you can find them at all (I believe they're all out of print, but are available from used-book sites like www.abe.com and www.alibris.com) will give you some detail on what Americans were singing, though less on what instruments they were playing. His "Popular Music in America," for instance, gives both lists and narratives covering popular songs decade by decade from the country's earliest days.

For individual songs and genres his work can be supplemented at sheet music sites like American Memory, as mentioned by others in this thread. But Spaeth is important for perspective and a framework. Wish there were more popular music historians of his caliber today!

Great research topic for someone to tackle, but very hard to research due to the scarcity of good evidence.

Bob