In the summer of 1848, the New Haven Railroad's first scheduled line came through Darien.

General business activity soon shifted from the harbor by Gorham's Mill, where the market boats had anchored for 150 years, to a new center by the railroad station at the Post Road crossing.

Until the advent of the railroad, Darien was a small, rural community of about one thousand farmers, shoemakers, fishermen, and merchants engaged in coastal trading. A gradual increase in population then occurred with the arrival of immigrants from Ireland and later from Italy.