What the map can—and cannot—say.

Retrieval and caching

City adapters request practical, date-filtered windows from each official API. Normalized responses are cached server-side so ordinary visits do not repeatedly hit city systems. If a source fails, StreetLens preserves the last successful response and labels it with its retrieval date.

Normalization

Chicago, Philadelphia, and Baltimore publish different fields and classifications. StreetLens maps the supported fields into a common incident schema while retaining each source agency, dataset, link, and data-quality note.

Grouping

When a dataset contains victim-level rows, records sharing the strongest available official identifier, date, and location are grouped into one map incident. The visible victim-record count reflects the number of grouped source rows.

Location privacy

Only source-published block-level or approximate locations are shown. Display coordinates receive a small deterministic offset to reduce residential precision while preserving neighborhood-level patterns. Records without usable coordinates remain eligible for appropriate statistics but are never placed at a city center.

Important limitation

StreetLens displays records published by official public-data sources and selected externally sourced materials. Records may be delayed, revised, incomplete, or classified differently by each agency. Locations are approximate. An incident record does not establish guilt, liability, or a complete account of what occurred.