A look at how households distribute across income levels — and what two numbers reveal about the economic character of a community.
Income distribution shape is one lens on economic character — where people cluster relative to the local median, and whether the middle is holding or hollowing.
What we don't yet know is exactly how middle-class erosion connects to housing unaffordability, and how housing unaffordability connects to homelessness. The path almost certainly runs through housing cost burden at each income tier — not just at the median — and probably involves time lags of years between cause and effect.
That's the thread we're pulling.
* University counties (Kittitas and Whitman) are dimmed in the scatter plots and excluded from trajectory analysis. Both counties host large state universities (Central Washington University and Washington State University, respectively) whose student populations are counted as households in the American Community Survey. Students living on financial aid, stipends, or part-time wages appear as extremely low-income households, inflating the share of the population below 30% AMI. This artificially elevates both the Gini coefficient and the Wolfson polarization index, making these counties appear more unequal and more polarized than their non-student economies would suggest. The effect is substantial: Whitman County (Pullman) consistently registers the highest Wolfson score in the state, driven almost entirely by this student population artifact rather than genuine market polarization. The data is not wrong — these households do have low incomes — but the structural interpretation is different from a county where low-income concentration reflects housing market failure.