Alley Frontage Lines for Cadastral Mapping in Washington, D.C.

Alley widths and street frontages were captured as linear features during a vector property mapping effort for the District of Columbia. The data, which resides in its own feature class, is described as being coincident with square boundaries 99% of the time, with exceptions for internal alleys overlaid by tax lots. It was last updated on 2026-03-25 and is provided by the District of Columbia under a CC-BY-4.0 license.

Use Cases

• Creating alley polygons for continuity within city squares based on linear features with specific classification codes.
• Delineating property lot boundaries by clipping square boundaries with tax and record lot data.
• Analyzing right-of-way and public access corridors based on alley width and frontage data.

Strengths

• Data is explicitly described as being coincident with square boundaries 99% of the time.
• Available in multiple geospatial formats including KML, GeoJSON, and via an ArcGIS REST API.
• Released under a permissive CC-BY-4.0 license.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• Description metadata is limited; actual data quality requires manual inspection after download.

Provenance

Source

District of Columbia

Collection Method

Captured during a vector property mapping effort.

Freshness

Last updated 2026-03-25 08:35:25.092550; freshness should be verified.

Geography

Washington, D.C., USA