Yea... I am not sure I understand the Boston metric on this chart right now. Boston+Cambridge are in a huge development boom. Residences and offices are going up all over the place and the project pipeline over the next 2 to 3 years is filled with a ton of stuff.

If Wikipedia is to be believed Boston added 18K people between 2010 and 2012. Between 2000 and 2010 it added 29,000. I think I also heard recently somewhere that in 2012 to 2014 Boston added another 10 - 15K people. The only thing I can think is Boston is being considered more than just Boston-proper but is including the entire Metro-west.

I think they are counting the graduating students as residents.

Not helping: I think they've done an exceptionally poor job of clarifying how they defined the metropolitan areas. For example, the label for the data in the Boston area (lifted off the map, which was the only place I could find the slightest mention) is "Boston-Cambridge-Quincy, MA-NH". Grouping MA and NH?! Conversely, Riverside and Los Angeles are separated despite covering a similar geographic range. I'd love to see the geographic regions in this study shown as polygons on a map, along with some sense of the total population per region.

They did an exceptionally poor job of defining metro areas. Separating Greenville and Spartanburg SC is dubious on its own but defining "Greenville" as the unimaginably small city plus the two smallest suburbs is a bit ludicrous. I know several companies that have individually relocated more employees to the region than this map credits for the whole metro area.

South Carolina has some weird outliers in terms of city limits and Greenville is one of them. The city itself is only 26.1 square miles and is mostly commercially zoned.

Cupertino and southern Marin County, Tracy and San Francisco have a similar geographic range. Are they grouped together? These are all quite different places to be. A lot of arbitrary choices need to be made when dividing areas. It's good to see what choices those were and why they were made.