"Overall, some 15 of the big metros grew at more than twice the 9.7% rate experienced by the entire country. One key reason — for at least some cities — was job growth ... However, not all the top growing regions in the country share the same economic trajectory ... Two things seem to stand out. One major factor seems to be affordability of housing ... The other major factor determining growth seems to be urban area density and size." (Quoted from article)