  In the light of the new data on the various neutron and proton
electromagnetic form factors taken in recent years, we update the
dispersion-theoretical analysis of the nucleon electromagnetic form factors
from the mid-nineties. The parametrization of the spectral functions includes
constraints from unitarity, perturbative QCD, and recent measurements of the
neutron charge radius. We obtain a good description of most modern form factor
data, with the exception of the Jefferson Lab data on G_E^p/G_M^p in the
four-momentum transfer range Q^2=3...6 GeV^2. For the magnetic radii of the
proton and the neutron we find r_M^p = 0.857 fm and r_M^n = 0.879 fm, which is
consistent with the recent determinations using continued fraction expansions.
