Smokey Bear is a campaign and advertising icon of the U.S.
Forest Service in the Wildfire Prevention Campaign, the 
longest-running public service announcement campaign
in United States history. The Ad Council, the United States
Forest Service (USFS), and the National Association of State
Foresters (NASF), in partnership with creative agency FCB,
employ Smokey Bear to educate the public about the dangers
of unplanned human-caused wildfires.     

A campaign began in 1944 featuring Smokey and the slogan
"Smokey Says – Care Will Prevent 9 out of 10 Forest Fires".

His slogan changed to "Remember, Only YOU Can Prevent
Forest Fires" in 1947 and was associated with Smokey Bear
for more than five decades, In April 2001, the message was
officially updated to "Only You Can Prevent Wildfires."   
(From Wikipedia, the free encyclopedia)