North Plains is a city in Washington County, Oregon, United States, off U.S. 26 on the northwest outskirts of the Portland metropolitan area. The population was 1,947 at the 2010 census.
Pioneer settlers first arrived in the North Plains area in the 1840s.
The area to be known as the city of North Plains was platted in September 1910 by the Ruth Trust Company of Portland. They purchased area tracts after James J. Hill planned to extend United Railways there.
On June 25, 1963, North Plains voted 90 to 56 to incorporate as a city; at the time the population was around 500.
Pumpkin Ridge Golf Club is just outside town. David Duval won the Nike Tour Championship there in 1993, and it was home to the U.S. Women's Open in 1997 and 2003. Horning's Hideout within the North Plains area was home to Faerieworlds Festival 2004
According to the United States Census Bureau, the city has an area of 0.90 square miles (2.33 km2), all land.
This region has warm, dry summers, with no monthly average temperatures above 71.6 °F (22 °C). However, temperatures are often above 100 °F (38 °C) for several days each year. According to the Köppen Climate Classification system, North Plains has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps.
As of the census of 2010, there were 1,947 people (a 21.3% increase from 2000), 706 households, and 511 families living in the city. The population density was 2,163.3 inhabitants per square mile (835.3/km2). There were 749 housing units at an average density of 832.2 per square mile (321.3/km2).