Convergence in U.S. Productivity Growth for Agriculture: Implications of Interstate Research Spillovers for Funding Agricultural Research

State crop, livestock,and aggregate agricultural total factor productivity (TFP) data, 1950–82, are examined for evidence of convergence to a single TFP level (σ‐convergence) or to a steady state rate of growth (β‐ or conditional convergence). Our empirical results do not support σ‐convergence but do support β‐convergence. The rate of β ‐convergence is variable and depends on research and development (R…D) spillins from other states,private R…D, and farmers' schooling. The finding of strong positive interstate spillover effects implies that independent state planning of agricultural research is inefficient and cooperation across states boundaries including establishment of new political jurisdictions for financing public agricultural research can enhance efficiency.