Update: Looks like a lot of folks were pretty far off on the estimates – Huntsville became the largest city in Alabama sometime back around 2017 or 2018. The official census numbers for 2020 put Huntsville at 215,006. So my discussion below is a bit outdated in places.

Folks like me that love to crunch population numbers have been pondering this for a very long time, wondering how valid it is to try to predict the future population growth of a city based on past performance. Sounds sort of like a financial advisors disclaimer. If anything, population growth in the area seems to be picking up the pace a bit within the past few years. If you juxtapose this population growth again big job announcements, I sort of get a qualitative notion that we are seeing a bit more organic growth than we have had in the past. That is, growth that simply arises out of economic momentum and good economic conditions, rather than being due strictly to big monolithic job announcements.

I did a little research on the biggest city in a state and how often that switches. As you might expect, it doesn’t happen often. The most recent switch occurred in Tennessee when Nashville became the largest city, replacing Memphis in 2015. The whole Nashville – Memphis population topic deserves its own blog one day. The next population switch (after Alabama, that is) looks like it will occur in New Jersey, possibly by the end of this decade, when Jersey City, population 262,075 in 2019 and growing at about 9.1% for the decade, overtakes Newark, population 282,011 and 3.4% growth rate.

So Huntsville looks to be poised to become the largest city in Alabama any day now. If you go strictly by the numbers from changes between 2019 and 2020, forcing the averages into smooth lines (which never really happens, I’ll admit) it will occur on Oct 31, 2021 – that’s Halloween! A friend of mine came up with June 29, 2021 (today as I write!) as the date of turnover. Not sure what his baseline data and assumptions are, though. I’ve arrived at those numbers by examining just the official census data between the years 2019 and 2020. Is it more reliable to use all data for the last ten years? That seems to have the advantage of a more consistent result, but the shorter basis, like I’ve used, may be more accurate.

Population Apples and Oranges
Since we are talking about population, I really should define here the different ways that you can measure the population of a city, along with their respective strengths and weaknesses. It’s very easy to confuse which population someone is talking about unless you keep these variations in mind.

• The City Itself
  This is what all this talk about Huntsville becoming the largest city in Alabama is about. It is just the population within the city limits. This has some obvious deficiencies, especially when compared to an areas larger metro population; the central city may be tiny (e.g., Hartford, CT) or it may engulf almost the whole county (e.g., Houston, TX). One step to alleviate this is to look at the next biggest area: the county.
• The County
  The county in which the core city resides is a good deal better at showing the true nature of the metropolitan area. Most counties (at least in the eastern U.S.) are at least in the same ballpark in terms of physical size, making comparisons more meaningful. As metro areas get bigger though, this also starts to be less effective as a measuring tool.
• The Metropolitan Statistical Area (MSA)
  Formerly called the Standard Metropolitan Statistical Area (SMSA), this is what most folks think of when they talk about the ‘metro’ area. It is a fairly accurate measure of the entire population of an area and it includes at least the county that the largest city is in. Typically as you look at larger and larger cities, you’ll see the MSA start to include adjacent counties in this number, thus bumping up the population number noticeably. This makes sense to measure an entire area this way usually (especially for measuring economic numbers), although it makes it a bit weaker for comparing the area to other smaller areas. which can be skewed due to the differences in size. A similar disparity is seen in comparing a ‘regular’ city against a city-county consolidated form of government (Nashville-Davidson versus Memphis is a classic example: Memphis is a ‘regular’ city occupying a part of Shelby County, whereas Nashville-Davidson (its official name) is almost the entire Davidson County). This disparity is mostly fixed in the CSA.
• The Combined Statistical Area (CSA)
  The CSA is bigger still than the MSA. It is a combination of two or more MSAs (including micropolitan areas also) that demonstrate economic or social linkage. The list of CSAs is almost half as long as the list of MSAs, meaning that almost all of the MSAs are also part of a CSA. Some of the really large metro areas have a dozen or so MSAs in their CSA! This is the largest entity among the various definitions of the term ‘population’.