Let me circle back and explain a little bit about how the definitions work and it might be a little clearer. This might be stuff you already know but in case not...and perhaps others might not either.
Metropolitan Statistical Area (MSA)
Region anchored by an urban area of 50,000 or more. Includes at least the county containing the core city but may include additional counties.
Micropolitain Statistical Area
Similar to an MSA but the core urban area is smaller -- usually 20,000-50,000. Again the "area" is the entire county.
Combined Statistical Area (CSA)
A primary MSA plus adjacent Metropolitan and/or Micropolitan areas defined by the census bureau to be functionally part of the primary metro.
The CSA was devised decades ago to reflect when separate entities grow together and largely function as one. The Dallas area is a good example. Both Dallas and Fort Worth are MSA's, and when they grew together enough to essentially function as one big metro area the Census Bureau did not strip Fort Worth of its MSA identity and roll it into the Dallas MSA. It created the Dallas CSA which is anchored by the Dallas MSA but includes some adjacent Metropolitan and Micropolitan entities including the Fort Worth MSA.
Simply being adjacent, however, does not mean two areas will be combined. There are markers of interaction and economic function (including things like commuting patterns) which the bureau uses to decide when a rural county should be added to an MSA and when adjacent metro or micro areas should be combined as part of a CSA.
I'll use an example I'm most familiar with to illustrate...the Milwaukee CSA. It is comprised of these elements
Milwaukee-Waukesha-West Allis MSA
The primary MSA...Milwaukee and its suburban counties
An adjacent MSA with ample economic interaction with Milwaukee MSA
Whitewater, Beaver Dam, Watertown Micropolitan Areas -- adjacent Micropolitan areas with ample economic interaction with the Milwaukee MSA
As I mentioned earlier, the website with the GDP information only lists it for Metropolitan areas -- none for Micropolitan ones.. So Milwaukee's number is missing the GDP from the counties in those three micropolitan areas (total population about 275,000.) Many CSA's have one or more Micropolitan areas as part of the CSA and those numbers are missing. By virtue of being "Microeconomic" areas none are especially large in GDP but they are not zero.
Once one gets beyond these officially-designated CSA's it gets especially difficult to know who to give credit to what -- it would be one judgment call after another. Going back to the Milwaukee service area, there are two more metro areas to the north adjacent to the official Milwaukee CSA, Sheboygan and Fond du Lac. They both send the large bulk their air traffic to MKE
but because the census bureau doesn't see ample economic interaction to roll them into the Milwaukee CSA they don't meet the "CSA" definition. The next adjacent entities north have no air service (Oshkosh and Manitowoc) and still probably send the majority of their air traffic to MKE
but significant amounts use ATW
-- there's no way to know how much. Going the other direction a mere 19 miles straight south of MKE
is the start of the Chicago CSA. The MKE
airport draws significant traffic from the northernmost counties of metro Chicago but there's no way to try to reconcile how much credit the MKE
market should get.
Can you see what a slippery slope it is to try to create one's own definition? That's why I stuck with the official CSA. If it helps you sleep better at night ignore the one deviation I chose to made by including Springfield as part of the Hartford/Springfield metro. Just use the numbers I posted for the official Hartford CSA alone. I can't say I always completely understand or agree with every inclusion/exclusion decision the bureau makes, but I don't have access to the data they do. They have not chosen to roll Clarksville into Nashville's CSA even though the southeastern boarder of the Clarksville MSA is adjacent to the farthest northwest suburban Nashville county. Apparently it's because Clarksville's function is more about Clarksville and is not feeding off of metro Nashville. I don't doubt that Clarksville's air traffic nearly all uses BNA
, but to make a reasonable comparison then every other metro area listed would need to be evaluated to determine what other entities should be rolled into their numbers. Adding Clarksville and Bowling Green would push Nashville's GDP number to 111,660, but many peers would rise as well. Even trying to put some sort of distance radius around an airport is just too messy to be useful. One can't simply say something like 150 miles is a reasonable catch basin because it depends very much on what other options also exist. Out west a metro area with little or no air service of its own 150 miles probably deserves includes. In other parts of the country an airport 150 miles away might be the 3rd or 4th closest commercial airport with significant service. There's just no good way to account for the true hinterland which feeds an airport. With the CSA definition at least it's something which was constructed based on (apparently) consistent, quantified criteria.
To help give more definition to what is included in the GDP number, here are the Metropolitan Areas included in the CSA. This may help clarify some questions...Portland does include Salem, Kansas City does include St Joe, Indy does include Columbus and Muncie, etc.
gdp.......chg 2001-2012......metro area
282741 ….. 63.6% ….. Seattle/Tacoma CSA (includes Olympia MSA, Bremerton MSA, Mt Vernon MSA)
243551 ….. 14.0% ….. Detroit CSA (includes Flint MSA, Ann Arbor MSA, Monroe MSA)
228301 ….. 50.8% ….. Minneapolis/St Paul CSA (includes St Cloud MSA)
201653 ….. 57.2% ….. Phoenix MSA
196187 ….. 50.8% ….. Denver CSA (includes Boulder MSA, Greeley MSA)
177410 ….. 55.0% ….. San Diego MSA
171124 ….. 83.3% ….. Portland CSA (includes Salem MSA, Albany MSA, Longview MSA, Corvallis MSA)
155107 ….. 32.3% ….. Cleveland CSA (includes Akron MSA, Canton MSA(
137189 ….. 67.8% ….. Charlotte CSA
136677 ….. 37.9% ….. St Louis CSA
127111 ….. 44.5% ….. Pittsburgh CSA (includes Weirton/Steubenville MSA)
124544 ….. 48.7% ….. Indianapolis CSA (includes Columbus MSA, Muncie MSA)
122023 ….. 46.3% ….. Kansas City CSA (includes St Joseph MSA, Lawrence MSA)
119926 ….. 54.8% ….. Tampa MSA
119611 ….. 59.0% ….. Orlando CSA (includes Deltona/Daytona MSA, The Villages MSA)
116002 ….. 38.2% ….. Hartford CSA (includes Norwich MSA) also Springfield CSA added
111247 ….. 78.3% ….. Salt Lake City CSA (includes Provo MSA, Ogden MSA)
108236 ….. 39.7% ….. Cincinnati CSA
101123 ….. 78.6% ….. Raleigh CSA (includes Durham MSA)
100512 ….. 39.5% ….. Columbus CSA
98677 ..….. 89.8% ….. Austin MSA
97576 ..….. 41.3% ….. Milwaukee CSA (includes Racine MSA)
97558 ..….. 53.4% ….. Sacramento CSA (includes Yuba City MSA)
95602 ..….. 69.5% ….. Las Vegas CSA
94789 ..….. 67.3% ….. Nashville CSA
91995 ..….. 78.6% ….. San Antonio MSA
88554 ..….. 65.4% ….. New Orleans CSA (includes Hammond MSA)
84836 ..….. 62.1% ….. Norfolk CSA
69016 ..….. 46.4% ….. Louisville CSA (includes Elizabethtown MSA)
68640 ..….. 30.9% ….. Greensboro CSA (includes Winston-Salem MSA, Burlington MSA)
68612 ..….. 47.0% ….. Richmond MSA
66778 ..….. 38.8% ….. Memphis CSA
63338 ..….. 71.2% ….. Oklahoma City CSA
62251 ..….. 55.9% ….. Jacksonville CSA
Anything which just says MSA has no adjacent areas rolled into their official top-level definition.
Anything which says CSA has one or more adjacent Metro or Micro areas rolled into their core MSA. But remember because there is no GDP info on Micropolitan areas those are not included here.