Allegheny CountyMap Index Sheets from Block and Lot Grid of Property Assessment and based on aerial photography, showing 1983 datum with solid line and NAD 27 with 5 second grid tics and italicized grid coordinate markers and outlines of map sheet boundaries. Each grid square is 3500 x 4500 feet. Each Index Sheet contains 16 lot/block sheets, labeled from left to right, top to bottom (4 across, 4 down): A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S. The first (4) numeric characters in a parcelID indicate the Index sheet in which the parcel can be found, the alpha character identifies the block in which most (or all) of the property lies.allegheny-county-map-index-gridengWestern Pennsylvania Regional Data Center Open DataPublicOtherAllegheny County Map Index GridDatasetsPennsylvania--Allegheny CountyPennsylvaniaLast Modified: 2026-02-21