Landauer conductance of Luttinger liquids with leads

We show that the dc conductance of a quantum wire containing a Luttinger liquid and attached to noninteracting leads is given by e^2/h per spin orientation, regardless of the interactions in the wire. This explains the recent observations of the absence of conductance renormalization in long high-mobility GaAs wires by Tarucha, Honda, and Saku Solid State Commun. 94, 413 (1995).