Below is a clean copy of a document comparing the data retention policies of the top five cell phone providers in the U.S. The document, entitled, “Retention Periods of Major Cellular Providers,” was produced in 2010 by the Department of Justice to advise law enforcement agents seeking to obtain cell phone records and was uncovered by the ACLU's coordinated records request on cell phone location tracking by police. The original  was received by the ACLU of North Carolina.
In August 2011, 35 ACLU affiliates filed 381 requests in 32 states with local law enforcement agencies seeking to uncover when, why and how they are using cell phone location data to track Americans. You can find more information about the effort here .