Complex sentence: Elected the 50th Governor of Virginia in 1925, initially, Byrd reorganized and modernized Virginia's government, and his political machine dominated state politics for much of the first half of the 20th century.
Split into simpler sentences: Elected the 50th Governor of Virginia in 1925, initially Byrd reorganized and modernized Virginia's government. His political machine dominated state politics for much of the first half of the 20th century.