Allegheny in Pennsylvania, drawn against the state outline.

Allegheny County is 83.5% non-Hispanic white across 1.28 million people, with a 12.4% Black share concentrated in and around Pittsburgh. Bachelor's attainment runs at 28.3% and the foreign-born share sits at 3.8%, both below what the county's urban core alone would suggest. Median household income of $38,329 and an 11.2% poverty rate point to a wide gap between the city and the surrounding municipalities. That split — a dense, more-educated urban center inside a whiter, lower-income county footprint — is the demographic backdrop to the cycle-by-cycle margin arc.