Which cities outside of SF are becoming large Startup Hubs?

I've recently seen more cities that are growing teams and building offices that seem to be growing rapidly? 

SF seems like it's one of many hubs that have been growing in the recent years. I'm trying to see which cities people are looking into and where people think will be the next startup hub? 

I've seen mixed opinions on cities like New York and Toronto but would love to hear what other people think as well!
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