Experiments were performed at room temperature to further understand the behavior of americium up to 100 GPa. In the experiments, both Syassen-Holzapfel (up to 60 GPa) and Cornell-type (up to 100 GPa) pressure cells were used. Possible structures following the application of pressure were determined. Am III and Am IV phases were successfully determined. New insights into the behavior of americium's 5f electrons under pressure and a mechanistic picture for the sequential conversion of americium from one phase to another under pressure were also obtained.