In the United States, the metropolitan statistical area (MSA) is a convenient and damning fiction. Here's a passage from the Census Bureau defining an MSA:
Under the standards, the county (or counties) in which at least 50 percent of the population resides within urban areas of 10,000 or more population, or that contain at least 5,000 people residing within a single urban area of 10,000 or more population, is identified as a "central county" (counties). Additional "outlying counties" are included in the CBSA if they meet specified requirements of commuting to or from the central counties. Counties or equivalent entities form the geographic "building blocks" for metropolitan and micropolitan statistical areas throughout the United States and Puerto Rico.
The core county (or counties) of an MSA is a function of population. But for other counties in the orbit, commuting patterns delineate. Many residents are connected to core county employment.
Within the MSA, residents have variable connections to core county employment. Some metro residents are part of the metro economy and some metro residents are not part of the metro economy. Boston:
And without a car, it’s almost impossible for someone in Mattapan looking for work to get to a place like Acton, he said. There is no bus service in Acton, a town of 22,000, and the commuter rail is miles from commercial shopping and can cost more than $10 each way.
Within the Boston MSA there is no commuting from Mattapan to Acton. But Acton needs cheap Mattapan labor. The two places are not functioning as one labor market within the same MSA. Thus, the two places are not functioning as one real estate market within the same MSA.
Within any metro is a tale of two labor markets. Some employees come from anywhere, in the entire world. Whatever they make, the sky is the limit. The other labor market is stuck. Stuck in wealthy Boston:
Adam Rutstein, the general manager, said sales are up and he’s hiring for every restaurant position except host. Filling those jobs is difficult in a town where unemployment was 3.3 percent last month, lower than the state average of 4.6 percent.
“Our talent pool is not Acton, it’s people who need hourly jobs,” he said, “so we have to pull from 20 minutes away.”
Most economists said it’s difficult to justify driving any further than that for a lower-paying retail or service jobs.
So the divide, said Megan Way, an labor economics professor at Babson College, ultimately “keeps people segregated.”
If you have a car, most economists say it's difficult to justify driving more than 20 minutes away for a job. For such labor, a metropolitan statistical area would be much smaller than the census would allow. Apparently, a metro area is as large as the wealthiest allow it to be.
Jim Russell, a geographer studying the relationship between migration and economic development, writes regularly for Pacific Standard.