This Shiny web app let’s you estimate the population within X miles of a point in the United States. It was motivated by a task that involved predicting the performance of new site locations for a grocery chain. Obviously population around each potential new site is an important feature, but determining those populations is not as simple as it sounds.
The US Census makes population estimates by census block-groups. In order to find the population within a circular buffer zone, we sum the population from all the block-groups contained in the buffer zone. Where the buffer zone cuts through a block-group, we make a naive assumption that the population in the block-group is evenly distributed and then use the percent of the block-group’s area within the buffer zone to estimate the percent of population within the buffer zone.