As one often does with Wikipedia, looking up one things leads you to something entirely different. I came across a table of the Combined Statistical Areas of the United States, defined as "an aggregate of adjacent Core Based Statistical Areas (CBSAs) that are linked by commuting ties" and is also the "the most expansive of the metropolitan area concepts employed by the OMB." I suppose a shorthand way of approximating this is, which NFL team does the network always show you on Sunday.
Anyway, I surprised to see Boston ranking much higher than I would have thought, coming in at number 5:
1) New York-Newark-Bridgeport
2) Los Angeles-Long Beach-Riverside
3) Chicago-Naperville-Michigan City
4) Washington DC-Baltimore-Northern Virginia
For comparison, Houston-Baytown-Huntsville ranks #9. If you were to look at a city based purely on its population, Houston is #4 and Boston is way down at #21. But, perhaps not surprisingly, a lot of people live near but not in Boston, while outside of the urban sprawl that is Houston, there is nothing. Certainly this matters when it comes to things like investing in transit infrastructure.