This one’s a bit of a cheat:
Laniākea Beach, Hawaii - pop. n/a
Laniakea Supercluster - total pop. unknown, but likely far greater than 7,000,000,000.
The question about the second largest city of the same name has come up before. The last time the best we could come up with is
Hyderabad, Pakistan 1.167 m
Hyderabad, India 3.637 m
(populations from Google)
According to the Board on Geographic Names database, there’s a Chicago in Kenosha County, Wisconsin.
Going by that database, the largest US city with a unique name is Fort Worth.
That’s interesting. Did you check all the names of the cities that a larger than Fort Worth in the database? That’s a lot of work! On the other hand, one can sort of guess by looking at a name whether or not a another place with the same name exists.
I would guess that next largest city (after Fort Worth) with a unique name is Albuquerque.
(I am using this list from Wikipedia, by the way: List of United States cities by population)
You’d probably let a name be the same if it was only a i to y substitution or something or a foreign spelling vs a modern english spelling.
So Newark … is a town in Yorkshire… It seems to be “New York” said in an accent. Basically if it counts it could win on sum of populations… or a point system that does the same thing.
Fort Worth is the 16th largest US city, so it wasn’t really that much searching. Especially since I could eliminate a number of names without searching. For instance, I know there’s a Dallas in Oregon, so no need to check that. I only had to check about half of the 15 names. Seven or eight searches is not very much work.
In that database, there’s only one Seattle. However, there used to be a Seattle somewhere in Texas. It’s long gone now. AIUI, it was a small town that sprang up near a WWII army base. When the base closed after the war, the town disappeared. But I have seen it on a WWII-era road atlas.
After that, Nashville-Davidson is unique, although Nashville by itself is not. Davidson is the county name and they hyphenated the names when the merged the city with the county. I don’t know how you want to count this.
For Oklahoma City, the database has a historical entry for a place in Illinois named Oklahoma, but which had a variant name of Oklahoma City. I suppose you’d count this if you count the Seattle in Texas.
After that, the next unique one is Albuquerque.
Actually, that’s The Dalles. 
But there are nine other Dallases in the U.S. besides the one in Texas.
There’s a Dallas in Oregon, too. I know because I once went for a job interview there. It’s west of Salem, not along the Columbia.
Wow. Very cool.
It would be great to know: 1. How many sentient beings live in this supercluster; 2. Of them, how many are AWARE that they live within it; 3. What do THEY call it?
2014 is an important moment, and few are aware of this. It has parallels with 1509 (I think that was the year), when Waldseemuller decided to put the word “America” on his new map of what informed Europeans were just starting to realize was an enormous, unexplored land mass.
There is Baltimore in the USA and Baltimorein Ireland with a population of 347.
Unless you’re only looking for both places within the USA.
Washington, DC (pop. 658,893) and Washington, VA (pop. 135) are notable for being about 70 miles apart.
What about Springfield, Minnesota? Population 2,152?
Another variation on the theme: Largest city which is larger than the the place it was named after:
I nominate New York City (population 8,941,000) named after York, England (population 204,000)
Honorable Mention: Portland, OR (population 619,000) was named after Portland, ME (population 66,000), which in turn was named for the Isle of Portland in England (population 12,400)
Technically, wasn’t New York named after a person?
I’m not really sure what it is about Maine except that you can drive through about 20 such towns in less than an hour…
“Springfield” is the town name that’s in the largest number of states.
There are quite a few states that have a town called “Lebanon”, too. I used to live in one of them - the one in Missouri, which is about 50 miles northeast of Springfield, MO.
There’s also Davenport, Iowa (pop. ca. 50,000, part of a multi-city almost 10 times bigger) and Davenport, Nebraska, which is a wide spot in the road.
How about the closest towns with the same name? There’s O’Fallon, Missouri and O’Fallon, Illinois, both part of the St. Louis metroplex. ETA: I see someone already brought this up.
Mexico and Paris are just a few miles apart - if you’re in Missouri. 
There are two places on earth where one can run a 26-mile race between Marathon and Athens. The other one is in northern Wisconsin. 
When I was a kid growing up in Iowa in the early 1970s, we regularly visited my grandmothers, who lived in small towns near each other just north of the Missouri border. I kept hearing about something terrible going on in Attica, and freaked out because I thought it was in the small town we passed through en route to Grandma’s house. My parents said, “This is another Attica, in New York.”
I didn’t know it was a prison riot until many years later - just that something really, really bad was happening there.
Come to think of it, these towns aren’t very far from Bowling Green, either. One time, when I lived in that region, the local paper printed some birth announcements from the Bowling Green Birth Center - the one in Kentucky, that is. They must have gotten a feed from somewhere and it slipped by the editor. Bowling Green, MO has a couple of doctor’s offices and that’s it; they don’t even have a critical access hospital, let along a freestanding birthing center. :rolleyes:
Now that the question has been answered, how about in the world? There is a Tokio, North Dakota and a Tokio, Texas. “Tokio” is an alternative spelling for Tokyo, and some sources think North Dakota’s Tokio may have been named after the Japanese capital.