Transition areas between metros
 

Howard County for Baltimore/DC and Mercer County for NYC/Philadelphia come to mind.

Hard to say where San Francisco and San Jose transition given that they're really the same metro in many respects.

Toronto and Hamilton are also increasingly one metro, but the suburb of Burlington is transitional between the two.

The 16 mile stretch of Camp Pendleton along the 5 freeway separates Oceanside in metro SD from San Clemente in Orange County/Metro LA. SD commuter rail and LA commuter rail overlap in Oceanside.

A 5 mile mountain pass between Rainbow and Temecula along the 15 freeway separate metro SD and metro Riverside. 9 miles between Fallbrook and Temecula.

Kenosha County is the pivot between Chicagoland and Metro Milwaukee.

Lake County is squarely in Chicago's orbit and Racine County is squarely in Milwaukee's orbit, which leaves Kenosha County in the middle, tugged both ways.

The OMB throws Kenosha into the Chicago MSA, but in reality it could go either way, it's a classic tweener zone.

The Trenton, NJ area is really kinda betwixt Philly and NYC. The Census defines it as part of the NYC CSA, but it's closer to Philly (around 30 miles, as opposed to 70-ish for NYC).

I think the city itself turns towards Philly, but suburbs like Princeton are pretty squarely in the NYC orbit.

Mercer County isn't a transition county. The commute patters are about 5-to-1 in one direction. A long time ago, when the county was mostly Trenton, yeah, it was probably a transition region.

Hartford is kind of a transition region. Richmond is another.

that sounds similar to kenosha's situation.

kenosha lies 50 miles north of downtown chicago, but only 30 miles south of downtown milwaukee, yet it apparently sends (or at least sent) more commuters into chicagoland (it does have a metra commuter rail connection into chicago) than it sends into metro milwaukee, so the OMB gives it to chicagoland, much to the consternation of some cheeseheads who believe that kenosha county rightfully belongs to metro milwaukee due to its location just north of the cheddar curtain.

in both these cases, the much greater gravity of the larger city of the pair is able to overcome the distance imbalance by pulling in more commuters.

but as i've wondered out loud many times now on this forum, i'll be quite curious to see what impact WFH will have on commuter percentages (particularly those of far outlying counties >50 miles away) and how that might reshuffle the deck a bit of our current MSA/CSA definitions, and even if we might need to find some new metrics by which to define them.

There is basically zero completely open country left between Cincinnati and Dayton, but development falls off out-of-sight of I-75.

and like a lot of old nearby city pairs, cincy and dayton don't exist in vacuum of completely vacant undeveloped rural land. in between them there are those older industrial towns strung along the miami river (hamilton, middleton, franklin, etc.) that have spawned their own mini-sprawl in the tweener zone over the decades as well.

so it's not just a simple case of two great waves of development, one from the south and one from the north, crashing into each other, but rather a much "messier" wave pattern of those two big macro-level waves combined with all of the mini-ripples of development pushing outward from those other smaller centers too.

All (or mostly all, especially southern) Delaware is between DC and Philly. There is still lots of vacant land and parts retain a rural flavor, but that is filling up with new residential and retail development. Delaware has low property taxes and no sales taxes. When I drove from DC to NYC, I used to take a detour around some of the I-95 tolls going via Baltimore by taking the Bay Bridge and the 301 past Middletown DE and then getting back on the I-95. It used to fairly empty land and mostly rural up 15 years ago, but now there are a ton of houses and retail, and they also threw in a tollway. The US census showed Delaware as one of the fastest growing states last year, and I suspect it is because DC/Philly and even NYC residents moved there.

Very true, and I agree re: Burlington.

I can't think of any other transitional areas between Canada's sparsely populated metros. Hamilton and Niagara maybe? The fringes of Montreal and Ottawa are about 1.5 driving hours apart (fringes), and even at roughly 6.0m combined between the 2 metros, there is no real transitional area due to lack of density between the two.

Given what's happening these days in Grimsby? Definitely. Ancaster is inching closer to Brantford, too.

Guelph these days is getting closer to being connected geographically to Kitchener-Waterloo-Cambridge. Kitchener fringe is 8km away and Cambridge fringe is 7km away.

Outside of southern Ontario I don't think there's really any others, though. Vancouver and Abbotsford? Canadian metros are faarrrr apart!

Not a lot of commuting these days, eh? But regardless, Mercer is the definition of a transition region not firmly/obviously part of either metro area; it has train lines that go to both 30th Street and Penn Station and gets TV stations from both metros. It is a little far from NYC's center of gravity although yes, more people commute there than to Philly. You can certainly argue that it's more NYC than Philly but it's really a grey area, which makes it the poster child for the thread topic.

The thing is those cities urban areas in Southern Ontario will not be touching anytime in our lifetimes. The Places to Grow act makes sure that their will be undeveloped areas between them.

Functionally they are the same metro, but in terms of visual appearance and developmental bones, San Mateo County would be the transition area between SF and SJ. As you go south from SF, you can see it gradually getting less and less dense and urban, and more and more sunbelt-y and suburban. Once you hit Mountain View and Sunnyvale, you can see a big difference, as you go from quaint Mid-Peninsula towns with walkable downtown districts to full blown autocentric suburbia.

Daly City - 13,734/sq mi
South SF - 7,366/sq mi
San Bruno - 7,799/sq mi
Millbrae - 6,851/sq mi
Burlingame - 7,145/sq mi
San Mateo - 6,700/sq mi
Belmont - 6,120/sq mi
San Carlos - 5,578/sq mi
Redwood City - 4,444/sq mi
Menlo Park - 3,473/sq mi
Palo Alto - 2,872/sq mi
Mountain View - 6,700/sq mi
Sunnyvale - 6,800/sq mi
Cupertino - 5,330/sq mi
San Jose - 5,685/sq mi

Obadno

These really only exist in true CSA/Megapolitan regions.

The Transiton zone beteween Phoenix and Tucson is .... Cassa Grande:

https://thumbs.dreamstime.com/z/agri...l-25474135.jpg

Exit 187 (aka) Airline Highway exit on I-10 is the transition point between metro New Orleans and metro Baton Rouge. Baton Rouge metro is to the west and New Orleans is to the east. On I-12, Hammond is the transition point. East of Hammond is fully metro NOLA and west of Hammond is fully metro BTR. Hammond is part of the NOLA CSA, but only by a slight margin. It's a fairly even commuter split.

Ann Arbor/Detroit buffer is everything west of 275 and east of US 23. The airport area is kind of weird too. Its super suburban north of 94 but everything south of the airport is basically out in the country. Portland and Seattle are pretty close the buffer is pretty big, Id say almost 70 miles between the fringes of each metro. Going south, Portland and Salem have basically bled into each other.

Oddly enough, I didn't notice much separation between Lexington and Cincinnati on 75. Maybe some farmland north of Georgetown, but it felt like one long(ish) slog through suburbia. I forgot how far south the Kentucky side of Greater Cincinnati has sprawled.

Miami, Fort Lauderdale, and West Palm Beach have continuous development between them, but the southern Everglade portion of Dade county and the Keys separate Homestead from Key West and much of Martin County before hitting Stuart separates much of the Treasure Coast from Jupiter in Palm Beach county. The northern gap is transversed by commuters via I-95, a drive I have done multiple times in my life.

Right on the line of Comal/Hays county between San Antonio and Austin is the last of undeveloped land between the 2 metros. Can't see it being more than 5-10 years before it's completely filled because of the insane growth of New Braunfels and San Marcos.