Allegheny CountyThis dataset overlays a grid on the County to assist in locating a parcel. The grid squares are 3,500 by 4,500 square feet. The data was derived from original MAPINDX: Map Index Sheets from Block and Lot Grid of Property Assessment and based on aerial photography. Tiles are numbered in a clockwise spiral fashion starting with #1 at the point in downtown Pittsburgh. Each tile contains 16 Blocks. 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-block-areasengWestern Pennsylvania Regional Data Center Open DataPublicCivic Vitality & GovernanceHousing & PropertiesAllegheny County Block AreasDatasetsPennsylvania--Allegheny CountyPennsylvaniaLast Modified: 2025-04-07