This is not true , I looked at Phoenix ,Denver and Las Vegas and there lots of power centers.May be not all those big box stores but lots of power centers in the 60's and 70's and also 80's .
I will post some pictures soon.
http://en.wikipedia.org/wiki/Power_centreThe first recognized power centre was 280 Metro Center in Colma, California, which was opened in 1986. A year later, Canada's first power centre, the Crossroads Centre, was built in Toronto.
Power centres began forming in the Greater Toronto Area in the late 1980s, and have since displaced nearly all traditional shopping mall development in the region, and to a lesser extent, the entire country. There are currently more than 300 power centres located throughout Canada.
Sure may be not box stores but there are power centers in the 60's, 70, and 80's to now.