Apparently Portland Oregon lead the way on this - by focusing in the early 90's on new zoning, bicycle pathways and greener parks, they became a nicer place to live, so people who could move (young,professional) choose to move there - and young professional people attract companies who want to hire them (not it turns out so much the other way round)

this seemed to work so well for Portland it also arose in other nice places to live and work - Denver apparently being a winner in that respect internationally too.