I don't think it's an engineering challenge, I think it's a cultural challenge. When traveling abroad, it's amazing how clean everything is. The amount of tras

I don't think it's an engineering challenge, I think it's a cultural challenge. When traveling abroad, it's amazing how clean everything is. The amount of trash on US highways, city sidewalks, public parks, etc. is pretty noticeable when you return. I'm sure we could build beautiful housing pretty affordably, but I'm not sure we could keep it beautiful unless we treat affordable housing as an ongoing investment and not just build it and forget about it.