For the wine region, see Napa Valley AVA. Napa County is a county located north of San Pablo Bay in the northern portion of the U.S. state of California. As of the 2010 census, the population was 136,484. The county seat is the City of Napa. Napa County was one of the original counties of California, created in 1850 at the time of statehood.
Area code 412 is a Pennsylvania area code that covers Pittsburgh and some of the surrounding areas. Area code 412 overlays the area code of 878. Pennsylvania has area codes of 215, 267, 272, 412, 484, 570, 610, 717, 724, 814, 878.
But overlays were a new concept at the time, and there was resistance to the mixing of area codes in the same area and the requirement for ten-digit dialing. As a result, 262 was made a separate area code for nearly all of the old 414 territory outside of Milwaukee County.ut overlays were a new concept at the time, and there was resistance to the mixing of area codes in the same area and the requirement for ten-digit dialing. As a result, 262 was made a separate area code for nearly all of the old 414 territory outside of Milwaukee County.