Samuel Slater's influence on Plainfield was evident in the early 1800's as small textile mills, powered by water and steam, began to appear along the Moosup River. The first of these establishments appeared in Moosup Village in 1809, when the Union Manufacturing Company built a small cotton-spinning mill. Two other textile mills followed this mill, the Cranska Mill (1817) in Moosup, and Central Manufacturing (1827) in Central Village. In 1853, yet another cotton mill, Wauregan Mills, was built along the Quinebaug River in the village of Wauregan. This growth of the textile industry in Plainfield in turn attracted other manufacturers to establish businesses around the mills.
The first railroad to run through the town of Plainfield was the Norwich to Worcester track, completed in 1839. In 1854, another railroad was laid down connecting Hartford and Providence. The Norwich to Worcester and Hartford to Providence lines intersected in an area of Plainfield later called Plainfield Junction. The railroads became the center of commercial activity, as businesses were established to provide food, entertainment, and hospitality to passengers on the trains. Overall, the coming of the railroads combined with the prevailing textile industry transformed Plainfield from a small agricultural community to a town growing in business and population, and on the brink of industrial prosperity.