What is the origin of the idiom "the right side of the tracks" and when to use it?

The origin of the idiom "the right side of the tracks" can be traced back to the historical division of neighborhoods or towns by railroad tracks. In many cities and towns, railroad tracks were built to connect different areas, and often, there was a socio-economic divide between the communities on either side. It is often employed to compare and contrast neighborhoods, cities, or regions, emphasizing the perceived advantages or disadvantages associated with each side.