The attached file (see related works above) has extrapolated population figures going out to 2035 for Minor Civil Divisions – cities and townships – located outside the seven-county Twin Cities region. These population extrapolations are based on simple mathematical formulas. They are controlled to county populations published by the Minnesota State Demographic Center in June, 2007.
The numbers do not reflect any special knowledge about individual communities such as zoning regulations, land available for development, current development projects, one-time events or any of the myriad other factors that can and do affect future population. The extrapolations are not a substitute for projections based on such detailed local knowledge and development plans.
Errors in the county projections will have a major effect on the accuracy of the Minor Civil Division extrapolations. If the county projections are too high, most cities and townships will also be too high. If the county projections are too low, the extrapolations for cities and townships within that county will be low as well.
Population numbers were adjusted for CQR changes. CQR is a U.S. Census Bureau program that allowed local governments to review 2000 census populations and report cases of population placed in the wrong city or township.
As far as available information permits, adjustments were made for changes in boundaries since 1990. Data on boundary changes is not complete, and changes occurring in the early 1990s are especially likely to be missing.
There were four extrapolation methods. In each method, Minor Civil Division projections were controlled to the projected county total.
A. Share of growth. Each MCD’s share of the growth or loss in the county population was calculated for the 1990-2006 period. In counties where every MCD was growing or declining, this proportion was held constant.
Most counties have a mixture of growing and declining areas. If the county is projected to grow, the growing MCDs receive all the growth while declining MCDs are kept constant. If the county is projected to decline, the declining MCDs share the loss while growing MCDs are kept constant.
B. Constant share. Each MCD’s share of county population in 2006 is kept constant in the future.
C. Exponential. The exponential annual growth rate from 1990 to 2006 is kept constant.
D. Linear. Average annual numeric change between 1990 and 2002 is carried into the future. Population is not allowed to go below zero.
Results: In many cases, the results of the four methods were similar, but in a substantial number of cases they were drastically different. Rapidly growing communities grew very fast in the exponential method. In counties with declining population, some communities fell to zero population in the linear method.
In the final stage, the high and low values were discarded. The numbers in the final table are the average of the two middle values.
For cities in the 7-county Twin Cities area, Metropolitan Council forecasts should be used. These forecasts use a completely different methodology that takes into account development plans, land availability, and so forth. They are available at: http://www.metrocouncil.org/metroarea/stats.htm