Clockwise from top: Downtown Portland viewed from east bank of the Willamette River; the Wells Fargo Center; Portland Aerial Tram and Mount Hood; Jackson Tower and Fox Tower viewed from Pioneer Courthouse Square; St. Its Combined Statistical Area (CSA) ranks 18th with a population of 3,160,488. National Bank Building) is the largest city in the U. The city covers 145 square miles (380 square kilometers) and had an estimated population of 639,863 in 2016, Approximately 2,424,955 people live in the Portland metropolitan statistical area (MSA), the 25th most populous MSA in the United States.
Beginning in the 1960s, Portland is frequently recognized as one of the world's most environmentally conscious cities because of its high walkability, large community of bicyclists, farm-to-table dining, expansive network of public transportation options, and over 10,000 acres (4,000 hectares) of public parks.
During the prehistoric period, the land that would become Portland was flooded after the collapse of glacial dams from Lake Missoula, located in what would later become Montana.
Less than 10 miles from downtown, the Willamette River flows into the Columbia River, the fourth-largest river in the United States, which divides Oregon from Washington state. According to the United States Census Bureau, the city has a total area of 145.09 square miles (375.78 km and its center lies in southeast Portland. Helens, a highly active volcano 50 miles northeast of the city in Washington State, is easily visible on clear days and is close enough to have dusted the city with volcanic ash after its eruption on May 18, 1980.
Portland is about 100 miles upriver from the Pacific Ocean on the Columbia. Portland's cityscape derives much of its character from the numerous bridges that span the Willamette River downtown, several of which are historic landmarks, and Portland has been nicknamed "Bridgetown" for many decades as a result.
Portland's access to the Pacific Ocean via the Willamette and the Columbia rivers, as well as its easy access to the agricultural Tualatin Valley via the "Great Plank Road" (the route of current-day U. Route 26), provided the pioneer city with an advantage over other nearby ports, and it grew very quickly.