While the US Census (which was last taken on April 1, 2010) is formally conducted every 10 years, the Census Bureau periodically posts estimates of the Census population for all counties/parishes across the nation. And just yesterday, population estimates were released for all of Louisiana’s 64 parishes. What do these population estimates tell us ?

While Louisiana’s population growth has for decades been less than the national rate of growth, Louisiana’s growth has been steady throughout the first half of the decade. Currently, Louisiana’s (as of July 1, 2015) estimated population is 4,670,724, which is a 3.0% increase since the last time the Census was taken in 2010 (the national rate of growth was 4%).

And if the current rate of growth were to continue until the 2020 Census, Louisiana would grow 6%. This is a rate of population growth the state has not seen since the 1970s. Plus, this rate of growth would likely allow it to keep its six Congressional seats.

When we look at individual parishes, the story is similar to what it was after the 2014 population estimates: 36 out of 64 parishes lost population. Compared to 2014, LaSalle and Saint Charles Parishes went from losing to gaining population, while Richland Parish lost population between 2014 and 2015 when in the past it was a population gainer.

Population Change By Parish, 2010-2015

There are two takeaways from the Census estimates worth noting: (1) the massive population losses in Orleans and Saint Bernard Parishes after Hurricane Katrina in 2005 are more and more a thing of the past, as those two parishes again were the fastest growing parishes between 2010 and 2015, and (2) the “10/12 corridor” is increasingly becoming a line of demarcation with regards to population growth and/or loss regions. To illustrate, parishes located along I-10 or I-12 posted a 5% population gain between 2010 and 2015. Parishes along I-20 posted a 1% population gain, while the parishes along I-49 showed no population growth, and parishes not along an interstate highway showed a 1% population loss.

These population estimates are important because a variety of government bodies – from the U.S. House delegation to local governments – are geographically apportioned by its Census population every 10 years. And given that the next legislative reapportionment will be conducted before the 2023 statewide elections, there will likely be some statewide impact.

Such impact is likely to be noticed more at the state house level because their districts are roughly one third the population of a state senate district. And if we project population changes ahead to 2020, it looks (like it did with the 2014 Census numbers) that Orleans and St Bernard Parishes will “recapture” two of the four state House seats that were eliminated during the 2011 reapportionment. Furthermore, continued robust population growth along I-10/12 between Lafayette and the Mississippi line means that a new district is likely to be created either in Ascension, Livingston, Tangipahoa, or Saint Tammany Parishes, while a fourth new seat will likely be created in and around Lafayette.

Since the state House is fixed at 105 seats, those four gained seats have to be offset somewhere. Currently, it looks like Caddo and Jefferson Parishes could lose a seat apiece, a third seat would come from Central/northeast Louisiana, while a fourth seat could come from East Baton Rouge Parish. However, it’s important to emphasize that nothing is final until the official April 1, 2020 Census count (the July 1, 2015 figure was an estimate). And furthermore, internal legislative politics can and will play a large part in determining the specific seats that are added or eliminated.