Complex sentence: The track hosts both thoroughbred racing and harness racing; its first-ever harness race was run on September 1,1976 while thoroughbred racing commenced on September 6,1977.
Split into simpler sentences: The track hosts both thoroughbred racing and harness racing. Opened in the mid 1970's, Meadowlands Racetrack held its first-ever harness race on September 1,1976 while thoroughbred racing commenced on September 6,1977.