Why should we care about St. Tammany’s split from Metro New Orleans?

Starting with data released for 2023, the metropolitan statistical area (MSA), anchored by New Orleans — officially, the New Orleans–Metairie MSA — no longer includes St. Tammany Parish. Following a 2020 update published by the federal government and implemented this year, the New Orleans–Metairie MSA now covers seven parishes: Plaquemines, St. Bernard, Orleans, Jefferson, St. Charles, St. John the Baptist, and St. James. Additionally, a new Slidell–Mandeville–Covington MSA has been created, which consists only of St. Tammany Parish.

Why have these official definitions changed? The short answer is that a smaller portion of workers who live in St. Tammany are commuting to work in Orleans, Jefferson, and other parishes on the south shore of Lake Pontchartrain. This smaller portion no longer meets the criteria for St. Tammany to be included in Metro New Orleans. For a longer answer, keep reading below where we run down the details.

As a result of the change, the new official population of Metro New Orleans is lower than you might recall. According to the Census Bureau, the population of Metro New Orleans was 962,165 in 2023. If St. Tammany were included, the population under the old 8-parish definition would be 1,237,748 in 2023. The massive discrepancy between these two numbers is overwhelmingly driven by the official removal of St. Tammany’s resident population from the total rather than by population loss in the individual metro parishes. The bottom line is that, going forward, the official estimate will reflect a 7-parish region of under 1 million, not an 8-parish region of over 1.2 million. Without St. Tammany, basic measures of Metro New Orleans’ demographic and economic makeup will also change.

This change is important for data users to understand. We wrote this research note to explain why the change is happening and what it means. It closes with a few reflections about “regionalism” and the role of data in promoting it.