The most important transportation development came in the 1860s-the Napa Valley Railroad. The railroad was mainly a result of the efforts of Sam Brannan to support his new Calistoga Hot Springs Resort. Napa Valley Farmers and Napa townspeople opposed the railroad as an attempt to bypass Napa. In fact, the railroad provided very favorable to Napa as it brought more people into the area, increased land value and drew greater attention to Napa. Napa grew and soon controlled trade of the northern county.

The formation of a county government system in 1850 brought about the building of the first courthouse at the corner of Coombs and Second Streets. The City was slowly becoming established: by 1854 the town had forty buildings, mostly primitive and made of wood. The streets were dirt. The town was busy, with a theater, a company of minstrels and musicians, a jockey club and other urban offerings. As the county’s population approached 7,000 by the early 1870s, plans were prepared for the third courthouse, which is still in use today.