  Background: The spatial distribution of charge and magnetization in the
proton and neutron are encoded in the nucleon electromagnetic form factors. The
form factors are all approximated by a simple dipole function, normalized to
the charge or magnetic moment of the nucleon. The differences between the
proton and neutron form factors and the deviation of GEn from zero are
sensitive to the difference between up- and down-quark contributions to the
form factors.
  Methods: We combine recent measurements of the neutron form factors with
updated extractions of the proton form factors, accounting for two-photon
exchange corrections and including an estimate of the uncertainties for all of
the form factors to obtain a complete set of measurements up to Q^2
approximately 4 (GeV/c)^2. We use this to extract the up- and down-quark
contributions which we compare to recent fits and calculations.
  Results: We find a large differences between the up- and down-quark
contributions to G_E and G_M, implying significant flavor dependence in the
charge and magnetization distributions. The rapid falloff of the ratio GEp/GMp
does not appear in the individual quark form factors, but arises from a
cancellation between the up- and down-quark contributions. We see indications
that the down-quark contributions to the Dirac and Pauli form factors deviate
from the suggested 1/Q^4 scaling behavior suggested by a previous analysis.
Finally, while recent models provide a generally good qualitative description
of the data, the down-quark contribution to G_E/G_M and F_2/F_1 are not
reproduced by any of the models. Finally, we note that while the inclusion of
recent $\gmn$ data from CLAS modifies the high-$Q^2$ slightly, the tension
between these data and previous measurements at lower $Q^2$ has a more
significant impact, suggesting the need for additional data in this region.
