Complex sentence: Scheduled nonstops did not reach beyond California, Las Vegas, and Phoenix until the winter of 1969--70 when American Airlines started a Chicago nonstop route although direct, no change of plane service was operated to destinations in the east.
Split into simpler sentences: Scheduled nonstops did not reach beyond California, Las Vegas, and Phoenix until the winter of 1969--70 when American Airlines started a Chicago nonstop route. Although direct, no change of plane service was operated to destinations in the east.