Complex sentence: During his tenure as chief of the state park system, the state's inventory of parks had grown to nearly; he had built 658 playgrounds in New York City alone; of parkways, and 13 bridges.
Split into simpler sentences: During his tenure as chief of the state park system, the state's inventory of parks grew to nearly. By the time he left office, he had built 658 playgrounds in New York City alone, plus of parkways and 13 bridges.