What Happened?

The other day, I was driving through a neighborhood in the Denver Metro area (I won't name it), and what I saw was very sad. This is a neighborhood that is very much on the verge of ruin. Many of the homes were unkempt, many more vacant with several foreclosures evident in the neighborhood. This is a neighborhood very much in trouble, with many residents down on their luck with probably many on the poverty level. My question is what happened? This neighborhood was largely built in the late 70's through the 80's, so it isn't that old. It was also built by several large builders (some local, and some national) with a large variety of homes styles from entry level to executive level. The impoverishment was spread across the board though, in all home styles.

Now I happen to know that these same builders built the exact same homes in other neighborhoods throughout the metro, and that these communities are very well maintained and desireable places to live. So what happened? What forces cause two very similar neighborhoods to follow very different paths? One neighborhood stays a very desireable place to live, and where home values are maintained. Another seemingly deteriorates literally overnight. I do know that the homes prices in this neighborhood were lower from the get go, due largely to a differnce in land costs, for the same home. But is that the only answer? Or are there other larger socioeconomic factors at play? How do we as community builders try to keep this from happening? Is there anything? I ask, because I dislike it when a community I have worked on goes into decline..for any reason. (No I had nothing to do with this community, well before my time). Any thoughts?