Campaign finance records are sourced from San Antonio City Clerk filings (searchable at the City’s campaign finance portal). Each donor is resolved to a person-level identity across all their contributions. San Antonio caps contributions per candidate per cycle: $1,000 for mayoral candidates and $500 for council candidates (individuals and PACs alike), which is why per-donor totals here are far smaller than in cities without limits. Industry classification starts from the employer and occupation each donor reported on the campaign’s schedule filings, supplemented by federal (FEC) giving records, employer research, and manual review — donors we can’t classify are shown honestly as Unknown. "Firms with 3+ donors" highlights organizations that may have coordinated giving, though individual donations are legally independent.