Original: In the 1970s relatively large numbers of newcomers to Alaska came to Anchorage, then relocated 40 m up the Glenn Highway to the largely rural Matanuska Valley where a "Alaskan country" lifestyle pervades.
Simplified: In the 1970's lots of newcomers to Alaska came to Anchorage. Later on a lot of them moved to the Matanuska Valley to live an "Alaskan country" lifestyle.