Complex sentence: The series covers a twenty-year period, opening in 1827 when the Steeds move from Vermont to western New York state, and ending in 1847 when they settle in the Salt Lake Valley.
Split into simpler sentences: The series covers 20 years and opens in 1827, when the Steeds move from Vermont to western New York state. It ends in 1847, when they settle in the Salt Lake Valley.