> I've never heard of a single suburb being an economic center, what would be examples of it in the US(?)

Silicon Valley, for one. Most SV companies are in the suburbs.

Google in Mountain View, Facebook in Menlo Park, Apple in Cupertino, EA in Redwood City, etc...

In many of those places you list, much of the economic activity--maybe most of it--is actually spread out over the suburbs associated with the city rather than being within the city limits. And this was certainly true prior to a lot of large businesses moving into places like San Francisco and Boston over the past 10-20 years. [ADD: And if you do go back a few decades, there were lots of examples of prosperous suburbs and cities which, if not failing, weren't in great shape.]

Boston that people talk about is really Boston and surrounding cities, much like New York City is made up of the 5 boroughs with Manhatten being New York County, Boston proper includes a few different cities inside of it like Mattapan, South Boston, Roxbury and the Greater Boston area includes Somerville and Cambridge. Many people outside of NYC would easily confuse Long Island as being part of NYC since it's part of the metro area.

Ironically, part of the reason traffic in Boston is so poor is due to not wanting to destroy poorer areas when roads were being built.

Route 128, "America's Technology Highway", is at the edge of the Greater Boston area. It would certainly have qualified as an 'economic center' back in its prime (through the 1980s at least).

https://en.wikipedia.org/wiki/Massachusetts_Route_128#.22Ame...