Poor South Carolina… borders Charlotte NC, Augusta GA and Savannah GA, so just missed out on 3 more cities. Is there a state with more? Use your own definition of what constitutes “neighbor”, “border” and “city” (although I’d like to stick to generally recognizable cities and not obscure little towns).
Have to drop a little historical note.
Without even looking at these histories, I can say that the reason that communities grew up on one side of a border - any border, state or otherwise - is almost always due to people not wanting to pay taxes. There may be other restrictions or freedoms involved, of course, religious heritage, land grants from a particular patron, zoning restrictions, but tax tends to be the biggie.
So it didn’t just happen that SC missed it by a bit. Everybody else was deliberately avoiding it.
People familiar with SC can chime in and tell me I’m wrong here, but the situation is so generally true I’m sticking with this explanation.
New Jersey is bordered by New York City and Philadelphia, which are two of the largest cities in the country; in terms of combined population they almost certainly beat Augusta, Savannah, and Charlotte.
I like the New Jersey case. Another example might be Mississippi, which is pretty close to 3 cities in 3 different states: New Orleans LA, Memphis TN, Mobile AL
California has Carson City, Nevada; Reno, Nevada; and Yuma, Arizona on its borders.
And Indiana has Chicago, Louisville, and Cincinnati, and if you want to count it… Dayton.
Washington has Vancouver BC, Portland OR, Astoria OR, and Coeur d’Alein ID.
Also reasonably close to Nashville TN, Birmingham AL, and Little Rock, AR.
You’re wrong. How on earth would people coming to Oglethorpe’s Colony in Georgia have any idea what would happen 200 years later when land nearby was settled and eventually became a different state? No one ever fled Rock Hill because Charlotte taxes were lower.
These are all geographic accidents, no more. Certain cities benefited from geographic situation, political leadership, or plain luck. In fact, I’m trying to think of anyplace where your tax-avoidance explanation has any basis in reality.
If people move to avoid taxes, then how come Salem, Portsmouth, or Manchvegas never got a big as Worcester, Springfield, or Boston, Taxachusetts?
A good percentage of state boundaries are river valleys. Almost all cities lie in a river valley or are situated near an estuary.
The entire system of suburbs in the northeast. Cities used to grow by annexing surrounding land. When the suburbs, mostly composed of wealthier individuals, started to grow significantly in the late 19th/early 20th centuries, they did not want to pay for the corrupt and money-hungry central cities. So they used their influence in the legislatures to stop easy annexation. That’s why every city in the Rust Belt started a long, slow decline over the 20th century as the middle class and higher left the cores to the uberrich and the poor.
The differing fortunes of metropolitan areas separated by a state line normally have taxes as explanation. The two Kansas Citys are a good example. You can also see this pattern in enclaves - administrative areas completely surrounded by a city. They exist widely, from Detroit to Los Angeles. These all have a tax history to explain them.
Lots of people have started threads about border towns, where you can buy fireworks or go to a casino, or in the old days find brothels or buy liquor, that weren’t allowed in the other state. That works in less obvious ways for cities like Gary, Indiana or Camden, New Jersey, or East Saint Louis, IL, where the state line meant that gritty stuff that wasn’t wanted even by the low standards of the central city could be located.
It’s a bit harder to see this pattern in today’s world until you take it down a level and note how malls, shopping centers, and industrial and office parks are situated. Monroe County didn’t want a mall and so the developers moved it a mile down the road to Ontario County. Now that starts miles of big box stores, strip malls, and chain restaurants. You can call it suburban blight and complain about traffic, but all that tax revenue floats every community in the county while Monroe drowns in debt. That same pattern can be seen everywhere. If you count zoning in, which I separated out but is really a variant on the same theme, even more areas are explained.
Money is almost always the driving force in development throughout American history. Sometimes you can make more money by staying in the center; sometimes you can make more money by leaving and going where it’s cheaper to operate. If you see a legal border in between those those places, then costs will change from one side to the other. And that makes all the difference.
One notable exception: Atlanta
Georgia itself has Chattanooga, TN and Jacksonville, FL just across the state line; it, in turn, has Augusta, Savannah, and most of Columbus, GA teasing the folks on the other side.
Exapno, you’re hilariously wrong, and you’re being hung on your own words here. Or rather, your second post is right, but it has got jack-all to do with the OP.
You yourself describe those borders becoming notable ex post facto. The borders didn’t cause the difference, and people didn’t start out doing the one because of the other. People did indeed move out of central cities, but it wasn’t taxes as much as high costs in general, of which taxes are but one small part. Likewise, differences in laws across borders has almost nothing to do with it, because those are inevitable across any border, no matter why it was created. But they didn’t cause peope to live there - if a city happens to grow near a border, you’ll end up with a lot of people on both sides because that’s how cities work. In other words, the borders didn’t cause the differentiation, and the differentiation didn’t cause the borders even in your own example.
Instead, you’re generalizing from a completely different subject. It’s like trying to use macroeconomics to explain the popularity of Sushi restaurants: nobody believes you, and you end up smelling like dead fish. 
Are we talking about any municipal entity or urban or near-urban settlement? Are we talking about a city qua legal jurisdiction with defined municipal borders? Or are we just talking about a substantial urban conglomeration, irrespective of jurisdictional borders? How close to a state border does it have to be to count?
It was a throwaway comment and wasn’t meant to hijack the thread.
I’m going to continue to insist that borders are meaningful and that siting a city on one side or the other happens for specific reasons. I’m not going to continue the hijack, though.
Dayton seems too much of a stretch, and not because of its size. There’s a whole county of nothingness between Dayton (or any of its proper metro area) and the Indiana border.
I doubt that places like Hoboken, Bayonne, Jersey City, or Union City in New Jersey were established because of the rich wanting to avoid taxes; they happened to the situated in a fine natural harbor (cities are usually established because of good transportation) in an area on the other side of the state border with New York. A shipping firm would find that location very attractive, no matter what the taxes were, and especially once space in Manhattan and Brooklyn was taken.
For what it’s worth, here’s an interesting piece about the secondary issue in this thread: