I vividly recall when you travel you’d throw your paper cups and trash out the window. It got so bad that they started a slogan campaign, and I think the winner was “Don’t Be a Litter Bug.” It was us kids that were mad at the grown ups. It didn’t take long, and the NOBODY threw garbage out the window.
The Highway Beautification Act was passed in 1964 at the urging of Lady Bird Johnson. As big a boor as her husband was, she was a Southern gentle lady and contributed a lasting improvement.