It was a racist question to begin with and pretty ridiculous one at that. So the residents in a community are now responsible for making their neighborhoods more diverse? How do you do that? When someone is selling you tell them they can only sell to certain race? How about just letting people live their lives how and where they want to without government getting involved.
The way to make a community more diverse is to welcome all races, ethnicities and religions. Who actually moves into the community will dependent on the cost of living and jobs. So a community with a high cost of living and more higher paying jobs who welcome minorities will likely have a more diverse religious population, more gay and lesbians, more European and Middle Eastern than Hispanics and Blacks. For poorer communities, the reverse is true.
What? Do communities post signs that say "white only"? If so I haven't seen them. Anyone can go live where ever they want in this country. With that said, neighbors can also keep to themselves if they wish. You're forcing your world view on others. Some people just want to be left alone to live their lives how they choose without anyone else bothering them, which is totally fine.
Yes, people can live wherever they want but people do not like to live in places where they aren't wanted. By electing city officials that are all white, no Jews, Muslims, Blacks, Hispanics sends a message to what type of town this is. Creating public spaces and parks only in white non-ethnic neighborhoods. Depiction of only White Americans in the public displays, murals, and statues and making sure all signs are in English only sends a strong message. However, the strongest weapon is the people of the town. By cultivating an anti-diversity environment, the town is sure to attract it's share of racists and people who have strong prejudices against those of other faiths and cultures, as well as those with un-American ideas.
A few well placed signs such as following popping up from time to time will get the message across.
Legacy Of Hate: The Specter Of North Idaho's Past Still Haunts Region