$70k isn't very tricky outside of "the most expensive places to live", and working in an urban setting doesn't mean you need to live next to the buildings you are designing.
Median household income, NYC: $58,000 ($35,000-77,000) http://www.baruch.cuny.edu/nycdata/income-taxes/med_hhold_in...
Chicago: $50,000 https://www.census.gov/quickfacts/fact/table/chicagocityilli...
If you're talking the SF Bay area, $70k might be quite a bit below median. https://www.census.gov/quickfacts/fact/map/sanfranciscocount...
Entirely dependent on your location. I'd imagine that most _ideal_ architecture jobs require an urban setting, which usually translates to high rent/housing prices, for which 70k might be a tricky budget.
If you're earning 70k in a strip mall sprawl, you might be better off financially speaking, but what opportunities exist there?