Compare this to the house I bought built in 1998, it is unlivable without the air turned on. And even with it running it is still uncomfortable when the temps get into the mid 90s. It has huge windows, but even with the curtains closed it was horrible -- there was just no natural airflow in it.
One of my favorite houses was one that a relative had in Mississippi, which was one roof with three separate living areas and a T-shaped breezeway running through the house. Another design item was apartments with sun rooms, where you could open various windows to always catch a cross breeze.
- Leaky ("breathable") home constructions vs. air-tight tolerances required to code now.
- Region-specific cooling and design practices which aided in the dead of the summer (or winter!)
- More geographically-minded decisions: Mature, treed lots for shade (double points for deciduous trees in winter which let the sun radiate through), more E/W facing vs N/S.
- Architecture: Smaller, closed off rooms (shut the door to trap the heat/cold), breezeways, enclosed porches all seemed a lot more popular then vs. now when keeping cool (or warm, in the rooms' case) was a priority.
Of course, mileage will vary, but this is something interesting I've found comparing the house I grew up in (built 1952), my first home (1986), and our recent build (2018) which are all within <5 miles of each other. FWIW, if the HVAC doesn't run all day at the new home, it's a noticeable "stagnant air" when you get home.
To put this into some perspective, some 2 billion live in Asia, Africa, and Latin American regions with the same or worse conditions re: heat and mosquitoes.
Galveston (where I currently live) was here long before A/C. The Storm of 1900 is what drove Houston to grow. Houston is more inland and better situated to weather the threat of hurricanes than a barrier island. The railroad allowed Houston to become a nexus of trade (in cotton shipping out of Galveston originally). The oil boom continued that growth. A/C didn't come along for many years later. It fueled the cities growth but plenty of people lived on the Gulf coast to benefit from the breezes off the water. In fact, it was those breezes that drove the University of Texas to start its medical hospital, UTMB, in Galveston.
How people managed to live further inland where there was no wind is beyond me. (There are too many mosquitoes to spend too long outside or have open windows without screens - besides, even then they'll still find a way to get through.)
A/C drove folks to move where the climates are warmer but land is more plentiful. A/C, like the railroad before it, made westward expansion more doable (bearable?).
Cities like Las Vegas and other desert metropolises sprang up as a direct result of A/C.