Projecting county-level populations under three future scenarios: a technical document supporting the Forest Service 2010 RPA Assessment
County-level population projections from 2010 to 2060 are developed under three national population growth scenarios for reporting in the 2010 Renewable Resources Planning Act (RPA) Assessment. These population growth scenarios are tied to global futures scenarios defined by the Intergovernmental Panel on Climate Change (IPCC), a program within the United Nations Environment Programme. The first of these scenarios, the A1/Census scenario, is equivalent to the current official U.S. Bureau of Census national projection, which, at the writing of this paper, extended to 2050. The second scenario, A2, is a higher population growth future, and the B2 scenario is a lower population growth future. The methodology for developing projections to 2060 is to disaggregate the above-mentioned national growth scenarios by using county shares of national population growth obtained from the Woods & Poole Economics Inc. projections of county populations from 2010 to 2030. A1/Census county projections from 2035 to 2060 are based on a recursive approach that extends past growth to project future growth, with adjustments to assure national additivity across counties and growth-dampening for the highest growth counties. The A2 and B2 county populations for 2010 to 2060 are derived from the A1/Census county projection shares.
Dataset cited on page 7 available here.