I have lived the past 13 years in 3 tiny towns (under 100); just go to the bar every night. Made both good shallow and good deep friendships like that while I was over 30 most of that time. Mind you that was in another country with another language than my native. Personally I get depressed by big cities much faster; people I met when living in those are far (acting) busier and so need to keep things shallow.
Also, I seem to have some thing that people find weird; I can make and sustain deep friendships via internet chat alone. I have friends I speak to every day, who would do anything for me and I for them who I do not even know what their voice sounds like. I have started, ran and sold companies with friends who I have never seen or voice chatted to.