Such factors as type of farm, farm production region, and farm size affect the percentage of farms hiring workers, the number of hours worked by hired workers, the length of the farm workweek, and the hours of labor used per $100 of sales. Labor costs and shortages most directly affected farms that sold $20,000 or more of farm products in 1964 and 1966. In 1966, these farms produced 68 percent of all farm products sold and used 68 percent of all man-hours of hired labor. Yet the farm family was the major source of manpower in both years. Regular hired labor was important on farms with $40,000 or more in sales and a major source of hired manpower for dairy and livestock operations. Workweeks were shortest for tobacco farmers, longest for dairy farmers and livestock ranchers. To produce $100 of sales, more labor was used on small farms, particularly tobacco farms, than on large farms in both 1964 and 1966. Data in this report were derived from information obtained in two Pesticide and General Farm Surveys conducted by USDA's Economic Research Service on 1964 and 1966 farm operations. This report presents data for farms having sales of $5,000 or more. (Author)