The limitations on carrier drift due to high-field streamlining of otherwise randomly velocity vector in equilibrium is reported. The results are based on asymmetrical distribution function that converts randomness in zero-field to streamlined one in a very high electric field. The ultimate drift velocity is found to be appropriate thermal velocity for a given dimensionality for non-degenerately doped nanostructure. However, the ultimate drift velocity is the Fermi velocity for degenerately doped nanostructures. Quantum and high-field effects con- trolling the transport of carrier in nanostructures are described.