In 2004, two researchers named M. Watt Espy and John Ortiz Smykia put together a list of executions that became known as "The ESPY File." The Espy File says that between 1608 and 1991, in the American colonies and then the United States, 15,269 people were executed. The Espy File is "the most often cited and used list of America's legal executions." However, in a 2011 study, two researchers criticized The Espy File. They wrote that researchers should not use the File as a complete source of information about executions.