The zoning is "Urban Neighborhood-UN" with single family zoning. Maybe it predates zoning? I can't find any details about it. I know they use urban and suburban zoning since my city merged governments between the city and county 10 years ago. Does it have more to do with tax benefits? 

@Zachary Peacock

Usually means that the district is a mixed use residential and limited commercial district with a density conforming to the local zoning codes. Every town/city has slightly different zoning codes, so you have to check with each one to determine what they allow or don't allow. Usually relates to lot sizes, building heights, allowed uses...

@Christopher Phillips Thank you for the response. I appreciate the insight. Good stuff.