Well, that kind of explains Putnam and the overall Huntington MSA, but I don't see any indication from those maps as to why Clay and Boone got slapped on to Kanawha unless they needed a consolation prize for losing Putnam.
I got side-tracked on the urbanized areas.
Delineation of urbanized areas does not consider economic ties, but is based on density. There is some interaction between the two cities because of I-64. Huntington Mall which is
the shopping mall for the regions is quite a way east of Huntington, and within easy travel distance of Charleston, if you want to do a little more shopping than Wal-Mart. Teays Valley is within commuting distance to both cities, and would be ideal for a couple with jobs in the two cities (e.g. one works at Marshall and the other works for the state government).
But Putnam is definitely tied to Charleston. Of workers who live in Putnam, 48% work in Putnam, 41% in Kanawha and 7% in Cabell, and 4% everywhere else.
Core-Based Statistical Areas (CBSA) are based around
an urban area core. CBSA based on an urbanized area (population greater than 50,000) are Metropolitan Statistical Areas. CBSA based on a urban cluster of more than 10,000 persons are Micropolitan Statistical Areas.
The first step in delineating a CBSA is to identify the central counties. A county is associated with the urban area which has the largest share of the county's population. In this case, more of Putnam is in the Huntington Urbanized Area (22K) than in the Charleston Urbanized Area (13K), so Putnam is a central county of the Huntington MSA (along with Wayne and Cabell, WV, Boyd and Greenup in KY, and Lawrence, OH.
A county may only be a central county of one CBSA.
Next outlying counties are identified. Counties where more than 25% or more employed residents work in the central counties of a CBSA are outlying counties.
Workers who resided in Clay worked 51% in Clay, 25% in Kanawha, 6% in Fayette, 4% in Nicholas, and 13% everywhere else.
Workers who resided in Boone worked 58% in Boone, 30% in Kanawha, 5% in Logan, and 7% everywhere else.
Both Clay and Boone are outlying counties of the Charleston MSA because over 25% of their resident workers worked in a (the) central county of the Charleston MSA.
Were it not for the flaw in delineation of the urbanized areas, Putnam would still be a central county of the Charleston MSA.
Note that the switch of Putnam occurred in 2010, not 2000.
This error also caused Lincoln to switch from Charleston to Huntington in 2010. More Lincoln workers worked in Cabell, Wayne, Putnam, and the other three central counties of the Huntington MSA than in Kanawha. Were Putnam still a central county of the Charleston MSA, then Lincoln would still be an outlying county of Charleston MSA. As it is, it might switch back based on the window used for measuring commuting. For 2010, they used the 2006-2010 ACS, but later windows put Charleston back in the lead.
Clay is quite small with only a little over 3000 workers. There doesn't appear much work in the county. Likely the school system and nursing homes. The town of Clay has less than 500 persons. There is a large strip mine on the Nicholas-Clay line, but access may be from the Nicholas side. It looks like a large number of persons in their 20s have left the county. You reach adulthood and there is not much to do, and few jobs, you leave. The alternative is to drive into Charleston. There is not a direct route, but I-79 runs along the edge of the county. A long commute, as much as an hour, but better than going hungry.
Unemployment is very seasonal, with a peak in January and a dip in June, swinging about 12% to 6% (this appears to be a decades long pattern, with the swing about 5 or 6$ regardless whether the peak is over 20% as it was in the early 20s, or 8% in the good times. This suggests that there are some seasonal jobs, either in recreation, or perhaps timbering or farming.
Boone is Coal Country. In fairly recent times. 20%+ of West Virginia production was in Boone, but this has dropped to under 10%. In the early 1990s, unemployment was around 20%, but had worked its way down to 3% by the 2008 recession. This could be due to a combination of people moving away, aging out of the work force, or mines reopening or adding production.
The unemployment rate shot up after the 2008 recession, and there was the threat that all four mines in the county would shut down. Unlike Clay, seasonal unemployment is more normal as the peak is reached in June, as people graduate from high school and begin seeking full time employment. If you are female, you probably won't be working in the mines, and if your husband may be laid off at any time, you may want a second source of income.
The ACS question is based on persons who worked the previous week. If you were laid off or on vacation, you won't indicate a workplace. Someone not working will decrease the denominator and increase the percentage of those who are working outside the county.
Workers outside the county bring the income home and spend much of it in the home county, where it pays for school teachers, police, doctors, cashiers, cooks, etc. So 25% outside workers is a high level of economic interdependence.
It is not unusual for a small rural county to be pulled into a MSA. There may be almost no jobs in the county. It also appears that working on a family farm
without pay is considered employment, but excluded from the commuting statistics. A small town may provide enough employment to keep a county out of a MSA. Rice is not in the Minneapolis-St.Paul MSA, even though Northfield is on the Dakota-Rice line and is commutable. Faribault is large enough to be a job provider in its own right, and it somewhat toward the southern part of the county. Mille Lacs is in the Minneapolis-St Paul MSA, in part because Sherburne is a central county, and commuting is counted even if it is just across the county line or towards St. Cloud), and because the population is concentrated in the southern part of the county. A surprising 10% of Mille Lacs residents work in Hennepin. This might include workers like airline pilots or firefighters, who may be out of the county for days at a time, but may also have several days at home.