Per capita personal income is determined by dividing Thurston County’s total personal income (or the income received from most major sources, including earned income, dividends, interest, rent, and transfer payments) by its population. This measure gives an average income for all residents, including children, retirees, and people who are unemployed.

Per capita personal income is often expressed in “nominal” or “real” dollars. Nominal dollars represent the actual dollar value at a specific point in time and does not include the effects of inflation. Real, or constant, dollars account for inflation and can be used to compare the buying power of money at two different points in time.