The law doesn't measure attitude it measures justice. In 1931, this was the reality in Boulder City. The town was owned by the U.S. Department of Reclamation. The town prospered, the people that lived there even those that do today are comfortable, there's a feeling a safety that permeates the streets lined with trees, a park in the center of town and a community that continues to thrive.
Diversity however? Not so much. Oral histories of citizens that lived here while the dam was being built will say there were no Blacks, Asians, and if there were Mexicans they cannot remember. According to historians Native Americans did work on the dam because it was believed they could scale the canyons better than a white man.
Nevertheless, was it only the law of the town, not the attitude of the people that made Boulder City a study of a worthwhile community?
If attitude is 99 percent what makes a person "positive" and worth being around, then the law that existed in Boulder City, 1931 was meant for people with good attitudes and the attitude would be of a people that respected the law and the ways and means of measuring justice.
Hence, attitudes change and so does the representation of these attitudes. The laws may change, but they are positioned to represent justice. What is justice? It is what the law decides it is and living "under" the law means by way of society you are just.