Santa Clara Thematic Atlas: Using GIS mapping to identify geographic disparities

Background: The Santa Clara County Public Health Department is often faced with the constant need to inform researchers and community members about city, neighborhood and census tract level health data. Disaggregating data at the sub-county or sub-city level has the potential to reveal disparities not otherwise evident for large geographies. As important as such data are, the methods to produce visually appealing data on small geographic areas are challenging and resource-intensive.

Objective and Purpose: The goal of the thematic atlas was to provide stakeholders and community members with a simple tool to help drive constructive data driven decision making in order to improve the community’s health and reduce disparities in Santa Clara County.

Methods: The Epidemiology and Data Management team worked with the Information Systems team in order to create a thematic atlas using GIS mapping and ArcGIS online for selected indicators in order to provide stakeholders and community members with a visual tool to extract socio-demographic, education, and selected safety indicators for the 15 cities, 109 neighborhoods and 372 census tracts in Santa Clara County. The interactive features provided by ArcGIS online allows end users to view disparities in and around sub-county regions.

Results: In its pilot version, the Santa Clara County Thematic Atlas included 10 indicators, including 2 age distribution indicators, foreign-born status, racial and ethnic diversity, household income and distribution, family poverty, child poverty, educational attainment, number of violent crimes and mode of commute at the three specified geographies. Each map in the portal allowed users to zoom and pan to compare data for each indicator across census tracts, neighborhoods, and cities, and provided additional detail and data on each small area indicator through interactive “pop-ups” and user-friendly search capabilities.

Discussion/Conclusion: Visual mapping can be very beneficial for data driven decision making and can provide stakeholders with a broader sense of disparities in surrounding geographic regions. The interactive mapping tool can also provide easy access to comprehensible and quality data specific to various regions and indicators. It can also contribute to informed outreach and the creation of health driven policies and practices.