EN
Grain yields and growing area of maize, wheat (winter and spring), soybean in the USA (without Alaska and Hawaii) in 1924-1993 was determined basing on the literature. The analysis of variability process of investigated features was carried out using trend function in the shape of linear regression. The above analysis results in the follwing conclusions: 1. All analysed cultivable plants are characterized by significantly positive yield trend with maize having the greatest average annual growth of efficiency. 2. Numerical coefficient of maize sbare trend in sowing structure appeared to be significantly negative, but for wheat and soybean, positive.