Country differences in population density has been previously negatively associated with country differences in fertility, where people from higher density areas had lower birth rates (Sng, Neuberg, Varnum, & Kenrick; 2017). So far, evidence concerning the relationship of population density and fertility has been limited to cross-sectional data and a priming study. The goal of this project is to explore the real-world societal-level relationship between population density and fertility using cross-temporal data.