Multi-state metros: why have some big cities shed so much population to their closest neighbors?

I enjoyed creating my first-ever listicle article a few months ago; it was New Year’s Eve, and I didn’t feel like revving up my gray matter.  And covering my most controversial blog posts was easy.  This time, I’ve decide to delve into something a lot wonkier—a lot more number-crunchy.  Sure, it’s just basic arithmetic, but it speaks incisively on how American cities have decentralized along certain patterns, and how political boundaries may actually skew the shape of those decentralizing forces more powerfully than, say, topography.  In the absence of a clear word or phrase for this listicle, I’m going to call it a “multi-state metro”, and I’m going to look at the interplay of those state boundaries by asking a critical question: what are the five US metropolitan areas where the non-prime, adjacent state or states distort the population the most?

What a bizarre question.  What could I possibly mean by that?

It’s difficult to articulate.  Those well-versed in US Census Bureau statistics or demography probably understand what I mean right away by a multi-state metro.  However, for the majority, the reality of course is that a metropolitan area has a layperson meeting and a practitioner meaning, and they don’t always align.  I like to reference the year 1945 whenever I reflect upon the history of American urbanism, and I’m going to do it again here.  In 1945, I suspect that the term “metropolitan area” didn’t get a great deal of use, even if demographers for the US Census Bureau had started exploring the term well before that date,  But in 1945, “metropolitan” almost certainly was not a household word (if it is today).  The Superman comics only debuted seven years earlier—probably the first time “Metropolis” achieved something akin to a mainstream reference, as Clark Kent’s home city.

(Incidentally, Superman’s debut year of 1938 coincided with the release of Lewis Mumford’s The Culture of Cities, where Mumford helped prompt the sociological salience of the term megalopolis, a concatenation of metropolises, and a term that Jean Gottmann further developed in 1961 with his eponymous work, applying Megalopolis to the near-absolute conurbation from the Washington DC metropolitan area to the south, stretching up through Baltimore, Philadelphia, New York City, and then Boston in the north.  I keep all this stuff in parenthesis because it’s a big digression, but it will play a role later in this article.)

Returning to the laypersons’ domain, terms like metropolis or metropolitan area served little purpose in 1945.  People had no reason to use such terms.  With few exceptions, metropolises as America perceives them today didn’t exist.  Sure, the nation had true-to-life inspirations on DC Comics’ Metropolis back then; New York and Chicago have been world cities for at least 150 years.  But the concept of a metropolitan area, consisting of a large central city and a ring of smaller suburbs, operating symbiotically a single urbanized unit—this was an incipient settlement pattern.

Prior to 1945, most Americans lived in either the countryside or a major city, usually no more than a few miles from the downtown.  The affluent management comprised the rare exception to the city/country dichotomy; these business-minded patricians began moving out to strategic stops on the outer segments streetcar or interurban lines—nodes that matured into streetcar suburbs, the first widespread use of the term “suburb”.  But these frontier villages, hugging the streetcar lines like the suction discs on cephalopod’s tentacles, were the exception, not the norm.  Streetcar suburbs in 1945 were growing in influence, but they represented a fraction of the population compared to the central city.  Suburbs in 1945 were not a major presence.  The term was not yet part of common parlance.  Every one lived in either the cities or the country (small towns or farms).

From an urbanism standpoint, 1945 was a pivotal year.  With World War II coming to a close, the young male soldiers returned home. to marry their sweethearts.  Many used the GI Bill to put a down payment on homes.  They bought cars.  And they had lots of kids, ushering in the Baby Boom.  Concurrent with all those babies came the first mainstream, widespread push to suburbanize.  And the term “metropolitan area” gradually achieved relevance outside of the demographers’ domain to characterize those adjacent municipalities still part of the big city’s urban region.  As the lower middle class began to suburbanize, in the 1950s and 60s, people freely used the term “suburb”.  Finally.

Washington eggheads favored the term a bit earlier.  The US Census Bureau first collaborated in 1949 with the Bureau of the Budget (the predecessor to today’s Office of Management and Budget, OMB) to develop a definition for Standard Metropolitan Area (SMA), consists\ing of a cluster of municipalities with a central city, typically the oldest and first-settled and the one to grow the most profoundly.  It’s also typically the largest municipality by far, in any suburban agglomeration.  For example, Chicago, despite having lost a fair amount of population from its 1950 peak, is still far larger (2.7 million people) than some of its biggest and/or most famous suburbs: Evanston, Naperville, Highland Park, Wheaton, Schaumburg, Oak Park, Cicero, and so forth.  Then again, Chicago has hundreds of suburbs.  The population of the Metropolitan Statistical Area MSA is over 9.6 million people, by 2021 Census estimates.

Not surprisingly, suburbs surged in popularity by the late 1950s, through a combination of people from the city moving out and newcomers to the region opting for these newly christened settlements in the purlieus.  The newest ones incorporated, eventually creating a patchwork of municipalities; the more mature ones grew from villages to minor cities.  By the 1960s, many historic cities were declining in population, even as the metros were growing.  People began to perceive metropolitan Chicago is “greater Chicago” or “Chicagoland”, defining the region by commuting patterns.  With most households owning at least one car, the metropolitan area—continuing the Chicago example—included any lands within a reasonable drive to downtown (Chicago loop), or even the city as a whole (plenty of jobs in other neighborhoods) or even the burgeoning employment nodes in the bigger suburbs.  The suburbanization stretched out to meet and engulf pre-existing satellite cities like Aurora, Elgin, and Joliet.  A century ago, these three satellites had nothing but cornfields separating them from Chicago; today the intervening lands are fully suburbanized.

The U.S. Census Bureau officially defined MSAs based on countries within the range of commuting to the original, historic, central city.  If a certain core percentage of people in that county commuted to the central city, it was sufficiently economically intertwined with the region; the Census considered it a suburban county.  Today, metropolitan Chicago includes 14 counties, stretching halfway across Illinois, partly into northwest Indiana, and even a little bit into Wisconsin.

And that’s where this consideration of a multi-state metro comes into play.  It’s about time..

Numerous major American cities sit right along a river or water body that also forms a state boundary.  With the ease in development of bridges (or tunnels, or ferries), it’s no surprise that some people opted to leave Manhattan, crossing the East River to Queens and Brooklyn and the rest of Long Island.  Or, more importantly for the purposes of this study, moving westward, across the Hudson River to New Jersey.  American cities big and small have generated multi-state metros.  So my nerdy urbanist question is: which ones have stretched the most from the “parent” state (the one hosting the primary central city) into the “child” neighboring state or states?  I measure this in terms of population: I divide the 2021 definition of a city’s MSA (total population) against the population of the counties in the neighboring state(s).  I gathered the census data for about a dozen multi-state metros that I thought could be contenders, then determined those with the highest percentage populations in the child state.  

Does it make sense?  I don’t want to get too bogged down in all the numbers for each winner, but I’ll take an example from a city that I thought would make the cut and didn’t: Memphis.

Nestled on the Mississippi River in the southwest corner of Tennessee, this multi-state metro stretches slightly westward across the river into Arkansas, then significantly southward into Mississippi, for which there are no geographic boundaries.  Just a perfectly straight horizontal line.  The Memphis, TN-MS-AR population in 2021 is 1,337,779 across eight counties.  Outside of the primary Shelby County (population 929,744), that contains the City of Memphis (population 633,104) the metro includes two other Tennessee counties, one county in Arkansas, and four counties in Mississippi: DeSoto, Marshall, Tate, and Tunica. The sum of these Mississippi counties is 256,912, comprising 19.2% of the Memphis metro total.  That’s a large share, but not enough to make my final cut.  Now it’s time to see the ones that rank.

Honorable Mention: St. Louis, MO and Illinois

MSA Population: 2.8 million

Illinois’ Share: 24.2%

Not terribly far upriver from Memphis, but on the other bank of the Mississippi River, this old Midwestern City lost a staggering amount of population in the late 20th century, by many respects more than the persistently ailing city of Detroit.  But, as a multi-state metro, many of the suburbs have thrived, including a significant number to the east in Illinois.  St. Louis, which has the unusual distinction of being a fully independent city (it does not sit within a county and only has the state government presiding over it), includes 8 counties in Illinois and only 6 in Missouri as part of its metro.  However, the majority of the suburban push has taken place on the Missouri side, with St. Louis County (enveloping a good portion of the elliptically shaped city) claiming over a million people.  As a person who grew up in Indiana, I remember I used to wonder why Missouri has always had a lower population than my home state, despite the fact that it has not one but two metros that are larger than Indianapolis—Kansas City only slightly so, but St. Louis quite a bit.  It comes down to political boundaries: the Show Me State’s two biggest cities sit right on the far east (St. Louis) and west (Kansas City) edges, and their MSAs spill over into the neighboring states of Illinois and Kansas to a considerable extent.  As of the 2020 Census, Indiana still has more than a half million people than Missouri, despite the fact that metro St. Louis and Kansas City are both bigger than metro Indy.  And St. Louis almost ranks in the top 5 multi-state metros with population fleeing from parent to child.

Honorable Mentions 2 & 3: Fargo, ND and Minnesota; Grand Forks, ND and Minnesota

At the eleventh hour, I’m going to add these two small North Dakota metropolitan areas, both of which sit along the eastern edge of the state, and their metros stretch across the Red River into Minnesota. Each of these two metros consists of two counties–one in each state. Fargo is North Dakota’s largest city totals just a little over 250,000 people; it claims 26.0% of its population’s share in Minnesota, though Fargo is exclusively in North Dakota. Meanwhile, a bit north up the river, Metropolitan Grand Forks has a population of just 103,000, barely enough to fit the Census classification of a MSA, but 29.7% of the metro population lives in Minnesota. I have never been to either of these cities and know little else to report, but the numbers track well: Fargo is a multi-state metro with more in its “child” state than St. Louis, my official honorable mention, and Grand Forks ranks higher (as a multi-state metro with population in the child state) than my number 5, as I’m about to reveal.

5. Chattanooga, TN and Georgia

MSA Population: 562,000

Georgia’s Share: 27.0%

Another multi-state metro contender from Tennessee!  Alas, I don’t have any photos of the Scenic City.  I have never been to Chattanooga.  And while it, too, is a river city, the Tennessee River bisects it; its municipal boundaries stretch on either side of this shallow, serpentine marvel.  And, much like Memphis to the west, the same parallel forms the southern boundary, though tis time it’s Georgia to the south, and the suburbanization has stretched comfortably that direction, offering nothing of geographic distinction that would indicate a state boundary—just a little sign.  Atlanta is only 120 miles to the south, and if that mega city (all within Georgia) keeps sprawling, some have speculated that someday, far into the future, metro Chattanooga and metro Atlanta could meet.  It’s already reasonable that a person may endure a long commute between one or the other, though that’s not yet a sizable enough portion of the population for the Census Bureau to consider fusing them into a southern megalopolis.  In thirty years, though…who knows?  For the sake of commuters, let’s hope that never happens.

4. New York, NY and New Jersey

MSA Population: 20.1 million

New Jersey’s Share: 34.3%

The nation’s most populous city and metro stretches across islands and channels and straits and rivers.  The network of bridges and tunnels elicited the “bridge and tunnel crowd”—visitors to Manhattan from the neighboring boroughs, the suburbs of Long Island, or, in a significant portion, the enormous mass of suburbs across the Hudson in New Jersey, making it a multi-state metro.  The major cities of Newark, Paterson, and Jersey City (the latter of which provides the photo view above, looking from the waterfront toward Manhattan) flourished on their own.  The three proliferated further as access across the river improved in the early 20th century, then each declined along with New York City during the troubling 1970s and 80s.  Each have experienced modest resurgences (Jersey City the most, Paterson the least) but also feature their own array of immediately adjacent suburbs; people fled from them just as much as from New York City.  Newark, a major urban center in its own right, largely operates as a metro within the metro.  And the three satellite cities alone contribute 750,000 people to the New Jersey sure of metro New York’s population.  To be fair, this number crunching isn’t entirely a fair representation of the full New York Metro, because it leaves out the suburban population in Connecticut, which, though nowhere near as great of a share as New Jersey, would actually reflect the CSA (Combined Statistical Area, a fairly new term) that captures the economic influence of a concatenation of metros that have grown into one another to form a multi-city megalopolis, evoking Mumford and Gottman from earlier.  Locals often call this multi-state metro “the Tri-State”. The CSA only characterizes a handful of mega-cities, but New York City is one of them.  Connecticut would push the New York City CSA well over 23 million people, but it would dilute the percentage share.  As it stands with the 20.1 million New York City MSA, twelve New Jersey counties fall into this suburban mix—almost all of the northern half of the state. Therefore, it wouldn’t be fair of me to use a different catchment area, so I kept it to the NY-NJ counties (with a tiny portion stretching into Pennsylvania).  This vast expanse of densely populated New York City suburbs is a major factor why New Jersey is and has long been the nation’s most densely populated state—more than Japan and comparable to Netherlands.

3. Providence, RI and Massachusetts

MSA Population: 1.7 Million

Massachusetts’ Share: 34.5%

A little further to the northeast, New England is replete with multi-state metros, primarily because the states are just so small—especially Lower New England, whose three states (Rhode Island, Massachusetts, and Connecticut) are also ranked second, third, and fourth respectively in terms of population density.   Therefore it’s no huge surprise that the smallest state in the country has a multi-state metro.  Providence is the second largest metropolitan area in New England (significantly behind Boston), and though its metro only includes one Massachusetts county (Bristol), it’s a sizable share of the metro’s population.  Providence is not far at all from the oddly jagged Rhode Island-Massachusetts border, and there’s no geographic barrier, so it’s easy for it to spread that direction.  Like Chattanooga and Georgia, the boundary is little more than a sign.  Meanwhile, the five Rhode Island five counties within the Providence MSA comprise the entire state.  With the exception of a few geographically constrained areas like Block Island, the entirety of Rhode Island rests within reasonable commuting distance to Providence.  New England treats its counties differently than the rest of the country; they have little political influence on their own and are measured as census units, so it’s likely that the unusually large Bristol County, MA only draws a portion of its commuting influence from Providence.  But I have to consider all MSAs under equal circumstances as articulated by the Census.  And, truth be told, Providence is merely the second most populous node in the Boston-Worcester-Providence-Manchester megalopolis—another CSA like New York, but that’s a framing device that I cannot consistently apply across all these metros, so I look at Providence in isolation.  And even then, a huge chunk of the metro lives in Massachusetts.

2. Kansas City, MO and Kansas

MSA Population: 2.2 Million

Kansas’ Share: 41.3%

Kansas City’s exact split as a multi-state metro is probably the most peculiar and also the most mundane.  Though a major city, I suspect the percentage of Americans who knows that it is two cities with the same name—and that the larger by far is in Missouri—drops off sharply outside of the Midwest.  Contrary to intuition, the Missouri side of Kansas City is significantly more populous, with a formidable skyline and population base that propels the Mid-America region into a considerable metro.  It’s the largest city in Missouri, though it has “Kansas” in its name.  Kansas City, Kansas (KCK) is essentially an old suburb of its neighbor, incorporated about 25 years later and never challenging it in population, though it has a moderately built-up downtown and claims over 150,000 people, while KCMO has over 500,000.  And though they touch one another—their boundary is conterminous with the state line—KCK and KCMO are two discrete cities, rather than one city founded along and stretching across a state line, as is the case with Bristol, VA-TN, with two mayors and city councils, because a municipality is subjugate to the state in which it rests.  Kansas City KS and MO have separate downtowns, not a single downtown split by a state boundary.  Kansas City Metro does include two major rivers; the Kansas River flows into the Missouri, but the Missouri River only forms a boundary for a small portion and Kansas City Missouri city limits straddles it.  Most of the boundary consists of the unassuming State Line Road, so suburbanization from the much larger KCMO was easy, and a huge portion went to Kansas, including five of the metro’s 14 counties, and most of the metro’s most affluent suburbs.  Johnson County, KS (JoCo) is the most populous county in Kansas and a major factor as to why Kansas gets such a high share of the population in this multi-state metro. No barriers, like Chattanooga and Memphis.  Just a road. 

Number 1: Washington, DC and Virginia

MSA Population: 6.4 Million

Virginia’s Share: 48.2%

Much like Metro New York City, this multi-state metro is a bit of a cheat, because it’s a CSA (Combined Statistical Area), with the suburbs of neighboring Baltimore having fully fused with those of Washington.  The southern end of Jean Gottman’s megalopolis, but also a megalopolis in itself.  Again, for the purposes of using a consistent framework, I have stripped away the Baltimore metro counties and looked exclusively at those more closely tied to the Washington DC economy.  (From the framework of the massive CSA, DC-Baltimore is a megalopolis of nearly 10 million people.)  But Washington DC MSA is an outlier as well, because, of course, the primary central city is not in a state; it is the District of Columbia.  As I noted in a recent article, since the 1847 retrocession returned the portion of District lands back to Virginia, the District of Columbia has exclusively rested north of the Potomac River, on the Maryland side.  But, of course, the DC population is completely separate from Maryland.  And, despite the formidable width of the river separating DC-Maryland from Virginia, the state opposite the river has absorbed an ever-growing share of the multi-state metro’s population.  By almost all metrics, more people influenced by the DC economy live on the Virginia side than Maryland, which, from my estimates, gets 40.1% of the MSA’s population share.  (The remaining 12% gets split among the District of Columbia itself and a few exurban counties in West Virginia.)  The DC metro may also be the most powerful example of suburbanization as arbitrage, because, regardless of how true it really is when one crunches the numbers, the perception remains that, thanks to property and income taxes, Virginia is the more affordable state in which to live.  As a result, the bridges across the Potomac River groan each day under the weight of commuting vehicles coming into the Federal Triangle or other employment nodes.  And our national capital, geographically configured with Maryland, is the multi-state metro where the neighboring state has siphoned off a greater share of metropolitan population than any other.  In a way it hearkens to the photo above, featuring the grave of Pierre l’Enfant, the visionary genius who designed Washington DC.  This relocated commemoration sits on a hillside in Arlington National Cemetery in Virginia, but looks out onto the District.  L’Enfant’s District.  Could l’Enfant have ever conceived that his vision would get to be so big that over 3 million people will spill out across the Potomac?

[For the sake of curiosity, I’ll list a few of the other multi-state metros that I explored, but, like Memphis, didn’t quite make the percentage share sniff test:

• Louisville, KY and Indiana
• Boston, MA and New Hampshire (and Rhode Island)
• Cincinnati, OH and Kentucky (and Indiana)
• Omaha, NE and Iowa
• Portland, OR and Washington
• Philadelphia, PA and New Jersey (and Delaware)
• Chicago, IL and Indiana (and Wisconsin)
• Charlotte, NC and South Carolina
• Springfield, MA and Connecticut
• Columbus, GA and Alabama
• Duluth, MN and Wisconsin
• Evansville, IN and Kentucky]