A forecast for the next two decades of growth estimates that the Portland metropolitan area will have between 2.7 million and 3.1 million residents by 2035.
That's a 400,000- to 750,000-person increase from the 2013 population of about 2.3 million.
"This region is a great place to live or to start a business and we expect that those same qualities will continue to attract people," said Metro planner Ted Reid in an email.
That growth is similar to the past – from 1990 to 2010, the seven-county Portland metropolitan area gained 702,000 residents, growing from 1.5 million to 2.2 million residents.
That includes both natural growth – the number of births minus deaths – and immigration from other cities, states and countries. About 40 percent of the region's growth comes from natural growth, with the remaining 60 percent of the growth coming from newcomers.
The projection is important – it's the baseline for the Metro Council's coming decision on the urban growth boundary. The council is required to ensure there's enough land for 20 years of growth within the UGB when it makes its decision on the boundary next year.
The population forecast is also used to inform policy proposals such as the regional transportation plan, and city and county planning efforts.
"Preserving farms and forests outside the city and revitalizing downtowns and main streets didn’t happen by accident – it’s because of intentional decisions made over the years," Reid said. "We want to make sure we provide policy makers with the best information possible so that they can continue in that tradition."
Because of its importance – the projection will be scrutinized by lawyers for developers and land conservation groups, as well as state regulators – Metro staff convened a committee of experts to advise them as they arrived at their projection.
The experts, from Portland State University's Northwest Economic Research Center, Population Research Center and Institute for Sustainable Solutions, as well as private sector firms like Johnson Economics, NW Natural and ECONorthwest, reviewed Metro's assumptions and the consulted on conclusions.
The final conclusion – the midpoint estimate of the regions growth – is just short of 600,000 residents. This midpoint is Metro’s best estimate for what the growth will be in 2035.
However, since predicting population growth is difficult, Metro provides a range forecast with 90 percent probability – there is a 90 percent chance, experts said, the region's growth will fall between 400,000 and 750,000 residents.
This growth forecast is for the Census-defined metropolitan area, which includes Clark and Skamania counties in Washington, and Clackamas, Columbia, Multnomah, Washington and Yamhill counties in Oregon. Of the current 2.3 million people that live in that 7-county area only about 1.5 million live in Metro's urban growth boundary.
This initial forecast is the first in a series of steps review the agency's growth management policies.
"In late July, we’ll release a draft of the 2014 Urban Growth Report, which will give people in the region a chance to consider how the region has been growing and what its challenges and opportunities are," Reid said. "In December, we’ll ask the council to consider this report as a basis for moving forward with a regional growth management decision in 2015."
As a part of that process Metro staff will begin to drill down to figure out how much of the growth will be distributed to different counties in the area. But, according to Reid, it is too early to tell how many of those 400,000 to 750,000 people will end up in Portland, Vancouver or even McMinnville.