Complex sentence: The annual wheat production of the United States more than tripled in the fifty years between 1871 and 1921; it increased from about 250 million bushels during the period of 1869-70-71 to over 750 millions during the period of 1919-20-21.
Split into simpler sentences: The annual wheat production of the United States more than trebled in the 50 years between 1871 and 1921. It increased from about 250 million bushels in 1869-70-71 to over 750 millions in 1919-20-21.