Per Capita Income (PCI) is one of the most widely used indicators for gauging the economic performance and changing fortunes of local economies. It is used as a yardstick to assess the economic well being of a region's residents and the quality of consumer markets. It serves as a barometer for calibrating the economic performance of a region over time and to judge differences in relative economic prosperity between regions. Shifting trends in local per capita income growth have important social and political ramifications and significant implications in formulating local economic development strategies and initiatives.

Personal income is measured as a flow throughout the year, while the measurement of population is at one point in mid-year. Therefore, per capita income is distorted if a significant change in population occurs during the year.

For smaller counties in particular, per capita income in any given year may be exceptionally high or low for the short run because of unusual local conditions, such as a bumper crop, a catastrophe, or a major construction project as the building of a dam or nuclear power plant.

Farm incomes are notorious for being especially volatile year-to-year, owing to changing weather, commodity market conditions, and alterations in government programs. Therefore, the per capita income of farm-dependent counties may exhibit sharp fluctuations over time.

The presence of large institutional populations--such as residents attending a local college or the residents of a local prison or state mental institution--can significantly lower the per capita income estimates of an area. Such results may not reflect the relative economic well being of the non-institutional population and may mislead if care is not given to their interpretation.

Figure 1 depicts Alameda County's annual per capita personal income over 1970-2019 in current and constant (2012) dollars. Constant dollar measurements remove the effects of inflation. They allow for comparison of changes in the real purchasing power of Alameda County over time.

When measured in current dollars, Alameda County's per capita personal income increased 1,509.6%, from $5,043 in 1970 to $81,171 in 2019. When measured in constant 2012 dollars to adjust for inflation, it advanced 207.0%, from $24,070 in 1970 to $73,892 in 2019.

Figure 2 tracks Alameda County's and California's annual real per capita personal income for the period 1969-2019 to illustrate real per capita personal income patterns over time. During this 51-year period, Alameda County's real per capita personal income rose from $23,527 in 1969 to $73,892 in 2019, for a net gain of $50,365, or 214.1%. In comparison, California's real per capita personal income increased from $23,360 in 1969 to $60,645 in 2019, for a net gain of $37,285, or 159.6%.

Figure 3 portrays Alameda County's real per capita personal income growth in a broader context by offering direct comparisons across time with California, the United States. The growth indices shown here express each region's real per capita personal income in 1969 as a base figure of 100, and the real per capita personal incomes in later years as a percentage of the 1969 base figure. This method allows for more direct comparison of differences in real per capita personal income growth between regions that may differ vastly in size.

Alameda County's overall real per capita personal income growth was 214.1% over 1969-2019 outpaced California's increase of 159.6%, and topped the United States' increase of 161.9%.

Figure 4 displays the trends for per capita personal income relative to the national average by tracing Alameda County and California per capita personal income as a percent of the national average over 1969-2019.

In 1969, Alameda County's per capita personal income amounted to 119.8% of the national average; in 2019, it approximated 143.7%. Similarly, in 1969, California's per capita personal income totaled 119.0% of the national average; in 2019, it consisted of 117.9%.

Figure 5 shows the short-run pattern of Alameda County's real per capita personal income growth by tracking the year-to-year percent change over 1970-2019. The average annual percent change for the entire 50-year period is also traced on this chart to provide a benchmark for gauging periods of relative high--and relative low--growth against the backdrop of the long-term average.

On average, Alameda County's real per capita personal income grew at an annual rate of 2.35% over 1970-2019. The county posted its highest growth in 2000 (10.47%) and posted its lowest growth in 2009 (-5.25%). In 2019, Alameda County's real per capita personal income grew by 3.56%

Over the past five decades some counties have experienced extreme swings in growth, and often such swings have tended to coincide with the decades themselves. Figure 6 again illustrates the annual percent change in Alameda County's real per capita personal income since 1970, but this time they are displayed with average growth rates for the decade of the 1970s, 1980s, 1990s, 2000s, and 2010-2019.

During the 1970s, Alameda County's annual real per capita personal income growth rate averaged 2.14%. It averaged 2.14% throughout the 1980s, 2.39% throughout the 1990s, 0.92% throughout the 2000s, and 4.16% thus far this decade (2010 to 2019).

Figure 7 compares the decade average growth rates for Alameda County noted in the previous graph with the corresponding decade averages for California and the nation. As the chart reveals, Alameda County's average annual real per capita personal income growth posted below California's average during the 1970s (2.14% vs. 2.16%), exceeded California's average throughout the 1980s (2.14% vs. 1.62%), surpassed California's average throughout the 1990s (2.39% vs. 1.73%), fell below California's average in the 2000s (0.92% vs. 1.12%), and led California's average over the 10 year period of the last decade, 2010-2019 (4.16% vs. 3.11%).

Finally, relative to nationwide real per capita personal income growth trends, Alameda County lagged the nation during the 1970s (2.14% vs. 2.37%), posted below the nation throughout the 1980s (2.14% vs. 2.20%), outperformed the nation throughout the 1990s (2.39% vs. 2.03%), lagged the nation during the 2000s (0.92% vs. 1.09%), and exceeded the nation over 2010-2019 (4.16% vs. 2.11%).