Complex sentence: New Haven rail line at Westport, Connecticut, took eight days to clear; transportation gridlock as a result of the storm was partially responsible for the creation of the first underground subway system in the United States, which opened nine years later in Boston.
Split into simpler sentences: New Haven rail line at Westport, Connecticut, took eight days to clear. Transportation gridlock as a result of the storm was partially responsible for the creation of the first underground subway system in the United States, which opened nine years later in Boston.