September 26th 1968
"On this day in 1968, President Johnson gave a message to the Congress transmitting National Science Foundation Report entitled 'Weather Modification'.

This program is a pioneering effort in man’s struggle to control his environment. In the coming years we must work with other nations to apply our whole range of technological skills to the problems of weather modification.

I commend this report to your attention.”
http://www.lbjlibrary.net/collections/on-this-day-in-history/september.html