We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in pp¯ collisions at s√=1.96   TeV using a data sample of 170   pb−1 collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution functions within the proton.