Every year one U. S. city is chosen as the "most literate" as explained in this blog post from 2005. In 2006, Seattle again ranked as most literate.
The survey has been done since 2005 by Central Connecticut State University. The website reads:
"Drawing from a variety of available data resources, the America’s Most Literate Cities study ranks the 70 largest cities (population 250,000 and above) in the United States. This study focuses on six key indicators of literacy: newspaper circulation, number of bookstores, library resources, periodical publishing resources, educational attainment, and Internet resources."