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Understanding Lightcast ZIP Codes and Related MSAs

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Overview

This document explains the structure of Lightcast ZIP Code data, how it compares to USPS ZIPs and Census ZCTAs, and what tools or resources are (or are not) currently available for mapping ZIP codes to Metropolitan Statistical Areas (MSAs). It is designed to help customers understand Lightcast geographies and resolve common challenges related to geographic alignment.

1. What Are Lightcast ZIP Codes?

Lightcast ZIP codes are a combination of:

  • ZCTAs (ZIP Code Tabulation Areas): Polygon-based geographic approximations of USPS ZIP codes created by the U.S. Census Bureau.
  • ZIP Points: Represent ZIP codes that do not have a corresponding ZCTA, stored as point data.

Due to technical limitations of shapefiles (which can't mix geometry types), these are stored in two separate files:

  • One for ZCTA-based polygons
  • One for USPS point ZIPs

Together, these files represent all ZIPs in Lightcast's coverage.

2. How Do Lightcast ZIPs Differ from USPS ZIPs?

  • Lightcast ZIPs are broader and may include areas not covered by USPS-only lists.
  • Clients using only USPS ZIP codes may notice mismatches when comparing to Lightcast data.
  • This hybrid approach improves coverage for analytics but requires alignment when integrating external ZIP-based data.

3. Current Limitations Identified

  • No direct ZIP-to-MSA crosswalk is currently available in the standard Lightcast datasets.
  • The taxonomy file LIGHTCAST.TAXONOMY.US_AREA does not include ZIP codes, making direct matching more difficult.
  • There is no ZIP-to-MSA normalizer tool for clients to use directly at this time.

4. Recommendations and Workarounds

  • GIS Overlay:

    • Customers with GIS capabilities can overlay ZIP polygons and points onto MSA boundaries to create their own crosswalk.

  • Latitude/Longitude Matching:

    • If USPS ZIPs are associated with lat/lon, customers can use a the [GIS API] to identify the closest or intersecting MSA.
    • This provides a generalized, scalable method to map ZIPs to MSAs, including those ZIPs not in Lightcast data.

Contact and Support
If you have further questions or need help with ZIP-to-MSA mapping, please contact [email protected].

Updated 2 months ago