An exact expression for the mass distribution rho(M; t) of the ballistic aggregation model in one dimension is derived in the long time regime. It is shown that it obeys scaling rho(M; t) = t(-4/3)F(M/t(2/3)) with a scaling function F(z) similar to z(-1/2) for z much less than 1 and F(z) similar to exp(-z(3)/12) for z much greater than 1. Applications of these results to Burgers turbulence are discussed. [S0031-9007(99)08466-5].