Complex sentence: The city's location on the deep Newfield harbor (mouth of the Pequonnock) fostered a boom in shipbuilding and whaling in the mid- 19th century, especially after the opening of a railroad to the city in 1840.
Split into simpler sentences: The city's location on the deep Newfield harbor (mouth of the Pequonnock) fostered a boom in shipbuilding and whaling in the mid- 19th century. Bridgeport's growth accelerated after the opening of a railroad to the city in 1840.