Complex sentence: By 1900, over 800,000 copies sold in the U.S., 40,000 in Canada and 100,000 in the United Kingdom, and by the 1930's world wide sales were over 7 million copies.
Split into simpler sentences: By 1900, over 800,000 copies sold in the U.S., 40,000 in Canada and 100,000 in the United Kingdom. And by the 1930's world wide sales were over 7 million copies.