In the reported study, the authors have started with a critical examination of published Mooney-Rivlin constants on the common commercial elastomers and some experimental ones. Following a suggestion by Treloar, plots were made of C//2/C//1 against 2C//1 in order to select values of the ratio at constant 2C//1 in comparing all elastomers. Cross-sectional areas of elastomer chains in the amorphous state were assumed to be proportional to areas for the same polymers in the crystalline state. A plot of log C//2/C//1 against log (area per chain) is linear with a slope of about minus 2. This is the first positive correlation of Mooney-Rivlin constants with a specific molecular parameter. Additional reports on the comprehensive studies are presented in six appendixes.