Complex sentence: Much of the United States used DST in the 1950s and 1960s, and DST use expanded following the 1970s energy crisis and has been widely used in North America and Europe since then.
Split into simpler sentences: Much of the United States used DST in the 1950s and 1960s, and DST use expanded following the 1970s energy crisis. It has been widely used in North America and Europe since then.