Students walk to classes at the University of Washington campus in Seattle on Nov. 12. Here's a look at the most-educated ZIP codes.

Four Northern California zip codes made the list of 30 best in the nation for families. Scroll ahead to see where they fall.

One Seattle ZIP code topped the nation for the largest "rent gap," with typical rent $875 below below the city average.

A Seattle tour map from 1965, two years after the U.S. Postal Service introduced ZIP codes. The ZIP codes were based on mail flow at that time.