This document summarizes a participatory mapping exercise conducted in Iringa and Njombe regions of Tanzania to identify HIV prevention and treatment service coverage gaps at local levels. Key findings from the mapping included higher than national HIV prevalence rates in the regions, with truck stops frequented mainly by migrant workers having low condom availability. The mapping data was then used by local decision-makers to advocate for additional HIV care and treatment sites in underserved areas. The document promotes engaging local stakeholders in data collection and sharing findings in accessible formats like maps to encourage use of local data for local health decisions.