We combine particle tracking and stochastic simulations to analyze the dynamics and organization of early endocytic vesicles in mammalian cells. At short time scales (<10(1) sec) vesicles exhibit 1D symmetric bidirectional motor-driven transport on microtubules such that the mean squared displacement (MSD) scales as t3/2, but the MSD shows a crossover to facilitated diffusion at longer times (>10(1) sec). Facilitated diffusion results in rapid equilibration of vesicles on microtubules. The asterlike organization of microtubules causes perinuclear accumulation of vesicles despite symmetric transport.