We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W(→lν)+γ production in eγ and μγ final states. Using data corresponding to an integrated luminosity of 4.2  fb^-1 collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp̅ →Wγ+X→lνγ+X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WWγ couplings for data from hadron colliders: -0.4<Δκ_γ<0.4 and -0.08<λ_γ<0.07 at the 95% C.L.