Complex sentence: Leland Stanford was an active Freemason from 1850 to 1855 when he withdrew, joining the Prometheus Lodge No.17 in Port Washington, WI, and then becoming a member of the Michigan City Lodge No.47 in Michigan City, California.
Split into simpler sentences: Leland Stanford was an active Freemason from 1850 to 1855, joining the Prometheus Lodge No.17 in Port Washington, Wisconsin. After moving west, he became a member of the Michigan City Lodge No.47 in Michigan City, California.