The National Digital Stewardship Alliance has released Web Archiving in the United States: A 2013 Survey.
Here's an excerpt from the announcement:
The goal of the survey was to better understand the landscape of web archiving activities in the U.S. by investigating the organizations involved, the history and scope of their web archiving programs, the types of web content being preserved, the tools and services being used, access and discovery services being provided and overall policies related to web archiving programs. While this survey documents the current state of U.S. web archiving initiatives, comparison with the results of the 2011-2012 survey enables an analysis of emerging trends. The report therefore describes the current state of the field, tracks the evolution of the field over the last few years, and forecasts future activities and developments.