Complex sentence: Racine was home to wagon maker Mitchell & Lewis Company in the 19th century, which, at the start of the 20th century, began making motorcycles and automobiles as Mitchell-Lewis Motor Company.
Split into simpler sentences: Racine was home to wagon maker Mitchell & Lewis Company in the 19th century. At the start of the 20th century the company began making motorcycles and automobiles as Mitchell-Lewis Motor Company.