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Oregon -- Population -- Statistics, Demographic surveys -- Oregon, Population forecasting -- Oregon -- Gilliam County


Gilliam County’s total population declined during the 2000s, with average annual growth rate of negative two-tenths of one percent (Figure 1); however, since 2010 the county has seen a slight increase in population, growing by more than 100 persons between 2010 and 2015 (Figure 2).

Gilliam County’s population decline in the 2000s was the result of a steady natural decrease and periods of net out-migration (Figure 12). The larger number of deaths relative to births has led to a natural decrease in nearly every year from 2000 to 2010. While net in-migration fluctuated during the early and middle years of the last decade, the number of in-migrants has been increased stably during recent years, contributing to population increase since 2009.

Total population in Gilliam County as a whole is expected to increase over the forecast period, with the majority of this growth occurring within Arlington UGB (Figure 1). Increasing net in-migration is expected to offset the growth in the natural decrease throughout the entire 50-year forecast period.

An aging population in the near-term is expected to not only lead to an increase in deaths, but a smaller proportion of women in their childbearing years will likely result in a steady number of births. During the final 31 years of the forecast period, the population is expected to shift toward younger ages leading to more births and a steady number of deaths. This combined with steady net in-migration is expected to lead to continued steady population growth.


This report is published by the Population Research Center at Portland State University, and is a product of the Oregon Population Forecast Program.

The introductory presentation, preliminary forecast presentation, and Gilliam County final forecast tables are attached to this document as supplemental files.

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R2_Gilliam_intro-pres.pdf (1233 kB)
Introductory presentation

GilliamCountyPreliminaryPresentation_rev.pdf (622 kB)
Preliminary forecast presentation

Gilliam_County_Final_Forecast_Tables.ods (51 kB)
Final forecast tables