The Department of Treasury’s release of IRS migration data immediately made me want to see for myself what Hurricane Katrina’s effect on Lousiana’s population was. The data is state and county level and based on tax returns.

I began by looking at 2005/2006 data and expected to find a decrease in population in 2006. What I found with this data is you have to read a user guide first. For example, one can’t just dive into it without knowing what FIPS codes are. As I continued to read I learned that my question probably can’t be answered anyway because, as the user guide states, “there are segments of the population that are not well represented by tax returns, most notably, the elderly and the poor.” Because most of the people the hurricane drove out of Louisiana were poor, I figured attempting to answer this question using this data would be futile.