Triple-overlay demo: 100 NC counties colored by 2023 median household income (ACS), with three stroke-only layers stacked above — state boundary (thick black), congressional districts (medium dashed grey), and state-senate districts (thin solid). Shows that boundary overlays compose; readers can quickly answer 'which CDs is this county in', 'which state-senate districts', 'how does income vary across NC' from a single map.