The 19th century turned New Hampshire's rivers into industry. In Manchester, the Amoskeag Manufacturing Company grew along the Merrimack into one of the largest textile manufacturing complexes in the world, drawing thousands of workers — many of them immigrants — into a planned mill city of brick mills, canals, and worker housing. Other cities built their own industrial identities: Nashua in manufacturing and textiles, Berlin in pulp and paper on the Androscoggin, and mill towns like Dover, Somersworth, and Claremont along their own rivers.
Railroads tied the mill economy together, moving raw cotton, wool, paper, coal, and finished goods between towns, ports, and the rest of New England, and bringing workers and visitors in. Around the mills and depots grew the dense downtowns and Main Streets — shops, banks, churches, and civic buildings — that still define many New Hampshire city centers.
The industrial boom did not last unbroken. The Amoskeag mills, long the heart of Manchester's economy, closed in 1935, a blow that forced the city and the state to reinvent the millyard for new uses in the decades that followed.