Christmas tree ornaments didn't really become popular in America until around the 1840's. Immigrants from Germany and England were bringing over their ornaments with them. Ornaments available at that time were mostly hand blown glass ornaments and German hand cast lead ornaments.
Check out these antique German ornaments from RelicRecord.com
In the 1880's, F.W. Woolworth stocked his stores with German ornaments. By 1890, he was selling $25 million worth of ornaments for 5 or 10 cents each.
Corning, was the first American company to jump on the Christmas ornament bandwagon. By using a machine that was meant to produce light bulbs, Corning was making over 2000 Christmas balls a minute. This was in 1939.
Check out this Christmas ornament advertisement from The Corning Museuem of Glass.
In 1973, Hallmark joined the Christmas ornament fun and introduced their Keepsake Collection. In doing so, Hallmark introduced a new tradition of Christmas decorating along with a new collectible. The first collection consisted of 18 ornaments total, 6 glass and 12 made of yarn. These ornaments were only available for a short amount of time. Since then, Hallmark has introduced over 100 series of ornaments and over 8000 different Keepsake ornaments.