Complex sentence: In 1848, Stephen C. Phillips and associates formed the Salem and Lowell Railroad Company, and by the summer of 1850 the railroad was opened; it terminated at Phillips Wharf in Salem.
Split into simpler sentences: In 1848, Stephen C. Phillips and his associates formed the Salem and Lowell Railroad Company. By the summer of 1850 the railroad was opened; it terminated at Phillips Wharf in Salem.