Complex sentence: When this celebration was first started, Mechanicsburg and the Surrounding area was almost entirely agriculture and much farm equipment and livestock was lined on the streets, since then, the new automobiles and many of the large industries have taken over exhibit areas.
Split into simpler sentences: When this celebration was first started, Mechanicsburg and the surrounding area was almost entirely agriculture and much farm equipment and livestock lined the streets. Since then, the new automobiles and many of the large industries have taken over exhibit areas.