  We report a new measurement of the pseudorapidity (eta) and transverse-
energy (Et) dependence of the inclusive jet production cross section in pbar p
collisions at sqrt(s)=1.8 TeV using 95 pb**-1 of data collected with the D0
detector at the Fermilab Tevatron. The differential cross section d^2sigma/(dEt
deta) is presented up to |eta|=3, significantly extending previous
measurements. The results are in good overall agreement with next-to-leading
order predictions from QCD, indicate a preference for certain parton
distribution functions, and provide the world's best constraint on the gluon
distribution at high parton momentum fraction x.
