PORTLAND, OR—The impact the tech sector has had on commercial real estate appears to be in one fell swoop but in actuality has been building since the financial crisis of 2008. The trend of start-ups and tech companies occupying large spaces in metropolitan areas is occurring all over North America and especially in tech-vital cities. So says Cushman & Wakefield’s annual report, Tech Cities 2.0, that identifies existing and emerging tech centers increasingly driving the North American economy and impacting the commercial real estate sector.