There has been school lunch programs in the United States for well over 100 years beginning with state initiatives that began in the late 1800's. The earliest federal aid came out of the New Deal era in the 1930's. The National School Lunch Act was approved in 1946 that provided funding and nutritional guidelines for school lunch programs. The Child Nutrition Act of 1966 was passed to extend, expand and strengthen the National School Lunch Program "under the authority of the Secretary of Agriculture as a measure to safeguard the health and well-being of the Nation's children, and to encourage the domestic consumption of agricultural and other foods, by assisting States, through grants-in-aid and other means, to meet more effectively the nutritional needs of our children."
The School Breakfast program was introduced as a pilot project in 1966 and made permanent in 1975. In 1998, Congress expanded the National School Lunch Program to include reimbursement for snacks served to children in after school educational and enrichment programs to include children through 18 years of age.
For a complete history of the National School Lunch Program to 1971, see The National School Lunch Program Background and Development by Gordon W. Gunderson at http://www.fns.usda.gov/cnd/Lunch/AboutLunch/ProgramHistory.htm