We use extreme-bounds analysis to assess the sensitivity of numerous control variables identified in the state growth literature. We employ annual panel data on the American states to identify which variables are robust to small changes in the conditioning information set. The results provide a set of core variables as a starting point for future research that relies on state growth regressions. The findings also demonstrate that several important conclusions in the literature depend on how variables are measured. (JEL R11, O23, C23, 018)