  We report a two-detector measurement of the propagation speed of neutrinos
over a baseline of 734 km. The measurement was made with the NuMI beam at
Fermilab between the near and far MINOS detectors. The fractional difference
between the neutrino speed and the speed of light is determined to be $(v/c-1)
= (1.0 \pm 1.1) \times 10^{-6}$, consistent with relativistic neutrinos.
