The population of the San Francisco-Oakland-San Jose metropolitan Bay Area is 8.3 million [1]. The population of the Baltimore-Washington DC metropolitan area is 9.3 million [2]. That doesn't seem that significant.

[1] https://en.wikipedia.org/wiki/San_Jose-San_Francisco-Oakland...

[2]https://en.wikipedia.org/wiki/Baltimore%E2%80%93Washington_m...