Validation of the Index of Relative Rurality Against Contemporary USDA and Census Measures

Defining and measuring rurality is a persistent challenge for researchers and policymakers. Threshold-based classifications often create artificial distinctions, failing to capture the continuous nature of the rural-urban spectrum. The Index of Relative Rurality (IRR) developed by Waldorff (2006) offers a continuous, multi-dimensional measure to address this shortcoming. This paper provides a contemporary validation of the IRR, testing a 2020 version of the index against the 2023 Rural-Urban Continuum Codes (RUCC), the 2024 Urban Influence Codes (UIC), and 2020 Decennial Census data on county-level rural population. Using ordered logistic regression, the IRR was found to be a highly statistically significant predictor of both RUCC and UIC classifications, explaining approximately 21% and 15% of their respective variances. Linear regression analysis revealed that the percentage of a county's rural population accounts for a substantial 57.4% of the variance in the multi-dimensional IRR score. These findings confirm that nearly two decades after its inception, the IRR remains a robust and relevant tool. It aligns closely with official governmental classifications while offering a more granular, multi-faceted perspective on rurality, underscoring its continued value for research and policy analysis.