<p>Household travel surveys are essential data sources for understanding travel behavior and informing transportation planning and policy. However, concerns persist regarding the representativeness of these surveys, especially in capturing the experiences of vulnerable traveler groups. Traditional performance metrics such as response rates offer limited insight into subgroup representation and can mask systematic biases stemming from survey nonresponse and noncoverage errors. To address these limitations, this study introduces the Group Representation Ratio (GR-ratio)—a novel, intuitive metric derived from sampling weights that quantifies how closely survey data reflect population proportions across key subgroups. We apply the GR-ratio to 43 U.S. household travel surveys—including the 2017 National Household Travel Survey and 42 regional and state surveys—to evaluate representativeness for four vulnerable traveler groups: low-income, transit-dependent, unemployed, and Black-led households. Results reveal substantial underrepresentation across these groups: 85% of surveys overrepresented white households, and only 11 surveys demonstrated reasonable subgroup representation. Importantly, we find that surveys using income-based stratified sampling, mixed data collection modes (e.g., GPS, online, smartphone), and targeted incentives are more likely to achieve improved representation for vulnerable subgroups. The GR-ratio provides transportation professionals and survey practitioners with a practical tool to assess equity-related performance and guide more inclusive survey design. While promising, this metric relies on careful subgroup definitions and survey item availability, warranting careful application and future refinements. By adopting more robust and equity-focused performance measures like the GR-ratio, transportation agencies can better support fair, evidence-based planning for all communities.</p>