Before revision:  The evolution of its wealth distribution is described by a nonlinear, nonlocal Fokker-Planck equation. In this work, we demonstrate that solutions to this equation fit remarkably well to the actual wealth distribution of the U. S. in 2013. The two fit parameters provide evidence that the U.S. wealth distribution is partially wealth condensed.
After revision:  The evolution of its wealth distribution is described by a nonlinear, nonlocal Fokker-Planck equation describing its time evolution and we describe its numerical solution, including a methodology for solving the inverse problem of finding the model parameters that best match empirical data. Using this methodology, we compare the steady-state solutions of the Fokker-Planck equation with data from the United States Survey of Consumer Finances over a time period of 27 years. In doing so, we demonstrate agreement with empirical data of an average error less than 0.16