I get that you work with what you have (in this case, a corpus of job postings), but a ranking that places Baltimore in the top three tech hubs fails the sniff test. CBRE has a better list here (email registration wall): https://www.cbre.com/research-and-reports/Scoring-Tech-Talen... I'm biased in that it places Atlanta unusually high, but overall it is a better, less surprising ranking: Bay Area Seattle New York Was…
NSA headquarters is in between Baltimore and Washington DC and there is a lot of other major government contracting work along that corridor. There is a lot of IT work available in the area, even if it isn't in Baltimore proper.