![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Socio-Economic Tools - Population Measurement
Population Projections
Population projections are the foundation upon which planning decisions
are based regarding the demand for future public and private services.
Population projections demonstrate if an area will experience increases
or decreases in their population. Typically population projections are
made for a twenty year period with five to ten year intervals. The following
tables and graphs demonstrate the use of population projections over a
thirty year period including a table which analyzes population changes
in the number of persons and by percentage. Population projections are
usually available from a number of different sources including: state
planning agencies; regional planning agencies; councils of government;
state transportation agencies; state water resources agencies; universities
or companies who develop and provide population data for a fee. Municipalities
can also develop their own population projection using a variety of available
models or basing projections on past growth patterns and the availability
of land for future development.
Population Density Forecasts- (in persons per square mile)
These forecasts are relatively easy to derive using population projection
data and the area of the municipality. See attached table.
House and Household Size Forecast
This provides interesting and useful information on the number of new
household formations (an important factor in housing and other service
demands) and household size. This projection information is fairly sophisticated
to develop and would usually only be available from a state, regional,
or county planning agency which routinely develops these types of projections.
Employment Projections- Employment projections are another important indicator of the economic growth and health of the community. These data are usually developed by employment sectors such as retail, office, industrial, federal government, state and local government, self-employed and other. This information may be available at a variety of different size areas ranging form counties to sub-planning areas. This information is difficult to develop and will usually only be available from state, county or regional planning agencies.
Information on changes in employment by numerical change and percentage may also be available and portrays the projected economic growth in the community. See attached table.
Build Out Projections
Build out data is a blend of population and housing data which demonstrates
increases in population and housing over a period of time and measures
whether either will meet or exceed a created build out figure for the
municipality. This can be an effective indicator of a communities need
to employ growth management techniques to manage or slow down growth if
projections will exceed the community's build out over the next twenty
years.
Housing Projections
Future housing needs are determined by three factors: population growth,
vacancy rates, and persons-per-household trends. Reduction in housing
vacancy rates reduces the need for additional new housing construction
by using more of the existing housing stock to accommodate projected population
growth. However the decline in vacancy rates can be offset by a reduction
in person-per-household ratios, which is occurring throughout the United
States. A reduction in persons-per-household results in the need for more
dwelling units to accommodate the same population.
The three factors of population growth, vacancy rates, and persons per household allow for a reasonable forecast of the demand for additional housing in a municipality. The attached tables demonstrate the historical and projected population, vacancy rates and persons-per-household trends and the resulting housing unit projection
Housing projections can be developed based upon the information and techniques described above. They are also usually available from state, regional and county planning agencies.