At least back to 1926. https://www.law.cornell.edu/wex/village_of_euclid_v_ambler_realty_%281926%29 https://www.law.cornell.edu/wex/village_of_euclid_v_ambler_r

At least back to 1926. https://www.law.cornell.edu/wex/village_of_euclid_v_ambler_realty_%281926%29 https://www.law.cornell.edu/wex/village_of_euclid_v_ambler_r... Industrialization led to many dirty cities especially before sanitation technology was deployed. Restrictions on more than e.g. 8 unrelated people per house, minimum window requirements, separating the meat packing district from a pure residential neighborhood were in response to tenements which were deathtraps in fires.