St. Louis City and County, are we that different?

St. Louis County and St. Louis City split from each other back in 1876 when the City was becoming more urban, while the County was farmland.  But now, that distinction is nearly completely erased as the County has grown to over 1 million residents living in neighborhoods that are much closer in design to the classic neighborhoods of the City than to the farmland of the 19th century.

People of 1876 would look at today’s St. Louis and probably ask why we have not moved the city boundary out to include all of St. Louis County and even most of St. Charles County.  The City and the County have a lot more in common with each other, than either has with the rural counties of Missouri and should combine, not only to take advantages of efficiencies that arise from higher density housing, but also to provide regional management for issues that require a regional level of decision making and project authority, as opposed to neighborhood, small city, or full state levels of authority.

There is a lot of data available at the “city” level, but city boundaries are political and not based on population.  Therefore, any city to city comparison within a larger metro area are always suspect because differences may just be driven by the random chance of where the city boundaries happen to have been many drawn years ago rather than being driven the item under study.  Rankings could change drastically just by redrawing a city boundary slightly. 

Zip codes within metro areas, by contrast, were originally set up roughly on an area/population basis to evenly spread out the job of delivering mail.  So, while not perfect, data based on zip codes within a metro area gets you closer to the truth than city statistics.

A site called, owned by the National Association of Realtors, presents a lot of data at the zip code level to help people who are evaluating a new place to live.  Compiling and plotting data from the zip codes in St. Louis County and St. Louis City show areas where we are different, of course, with regard to density, crime, etc.  But more striking are the plots that show how much St. Louis County and St. Louis city are not very different.

First, consider the percent of white collar jobs vs. blue collar jobs in both the City and County. 


According to, every zip code in the St. Louis County/St. Louis City are majority white collar except one, and that that one zip code is in the County.  Our metro area has truly transitioned from the old industrial factories of the past to a white-collar air-conditioned intellectual economy for workers in both the City and the County.

The City and County populations counts have not increased significantly in many years, as smaller families live in the smaller homes of the city than a century ago, and the county has been largely built out.  But look at the extreme East and West zip code areas of the City/County. 


The East and West extreme zip code areas of the City County region share the distinction of having the largest population percent increases since 1990.  Zip Codes 63030 in Wildwood, and 63005 in Chesterfield, finished in the top three (first and third) in biggest percent increases in population in the City/County since 1990.  They are two of the zip code areas furthest from St. Louis City Hall downtown. 

But they share the honor of fastest growing zip code with 63101 at number two right in the heart of downtown, the zip code that includes the St. Louis City Hall.  Downtown living has been booming and is the new frontier as much as the fields of far West County.  The zip codes in between these extremes are the built-out areas with populations slowly rolling up and down as large families transition to empty nesters then and get sold to young families to restart the cycle.

Average household size varies less than you might expect between the City and the County.  While the City may have more households with fewer residents than the County, most zip code areas in the City and the County are closer in household size than many might have expected, with no clear pattern visible other than much larger households in far far West St. Louis County where new very large houses are under construction.  Even with those anomalies, the average across both the City and County is about 2.3 people per household.  The average in the City is about 2.1 people per household, whereas the County averages about 2.4 per household. 


Figure 3 Average Household Size – St. Louis City and County

At one time, there was a presumption that the residents of the City were naturally older, since they purchased homes there in the early 20th century, raised families, and lived out their lives there.  However, now age differences between City and County are a mixed bag with median ages in the 20’s showing up in zip codes in both the City and the County.  Similarly, zip codes with 30’s as the median age pop up in both the city and the county with little relation to the City/County boundary, and in no predictable pattern.  Zip codes with median ages in the 40’s are spread throughout the County for now, just the opposite of what probably existed a century ago. Homogenization of generations will likely be the norm throughout the City/County area for a long time to come.  Average ages in zip codes of the City and County are shown in Figure 4.


Figure 4 Median Age for Each Zip Code Area in the City and County

The bottom line is that while there are some differences between the City and the County, the differences are nothing like the rural/city split of the 1800’s.  In many categories, the City and the County are already one people statistically, which is probably why we all call ourselves St. Louisans.