A simple answer is that there was more surface water and helped keep it cooler 150 years ago. For example, I lived in Tucson, AZ and there was a road nearby ca

A simple answer is that there was more surface water and helped keep it cooler 150 years ago. For example, I lived in Tucson, AZ and there was a road nearby called "Silverlake" that at one time led to a silver lake with enough power to support a flour mill (see https://tucson.com/news/blogs/streetsmarts/street-smarts-silverlakes-namesake-made-a-splash-powered-flour-mills/article_e2a9abb0-9ff7-5264-bb67-999d19d06b78.html https://tucson.com/news/blogs/streetsmarts/street-smarts-sil...). Now it leads to apartments and houses and an Air Force base. More people + less water = hotter environment, even before climate change is factored in. A huge amount of the water in the area goes to agriculture as well.