Since 1988, PBS has broadcast a series that focuses on the history of the United States and what has made it unique. Called The American Experience (now shortened to simply American Experience), the program examines the people, events, technology, and natural resources that have shaped the country. Hosted by David McCullough until 2002 and narrated by a number of well-known personalities - The American Experience uses historians and authors, period images and film, music, dramatic re-enactments, and contemporary context to set the stage for its topics. The series continues to this day with a variable number of installments produced each year. Episodes are generally 60 minutes in length, but some longer episodes and multi-part series have also been produced. The show airs at different days and times on local PBS stations. Though The American Experience has used many films from independent film makers and has been assisted by various PBS stations throughout the country, it has always been spearheaded by WGBH in Boston.