After the Second World War, Washington saw a record high level of income equality – the bottom 90 percent of the population captured 79 percent of the income in 1945. Through 1979, the bottom 90 retained about 70 percent of income, but the rate has declined steadily since, with the rate of decline accelerating during economic booms and modest rebounding during recessions. By 2012, the bottom 90 percent of households only received 50 percent of total state income. The other 50 percent went to the top 10 percent of households. The top 1 percent received over 20 percent of all state income in 2012, almost tripling their share since 1979.

Since 2013, real incomes have gone up for many Washingtonians, but the wealthy continue to capture an ever greater share of income in Washington, as shown in Figure 2. From 2010 to 2016, the mean income for the bottom 20 percent of the population increased 11 percent – but the top 20 percent gained 19.9 percent. The annual gap between the poorest and richest quintiles grew from $152,631 to $192,146.