Single-top-quark production probes the charged-current weak interaction of the top quark, and provides a direct measurement of the CKM matrix element V_tb. We perform two independent analyses to quantify the accuracy with which the W-gluon fusion (gq -> tb̅q) and (qq̅ -> tb̅) signals can be extracted from the backgrounds at both the Tevatron and the LHC. Although perturbation theory breaks down at low transverse momentum for the W-gluon fusion b̅ differential cross section, we show how to

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... a reliable cross section integrated over low b̅ transverse momenta up to a cutoff. We estimate the accuracy with which V_tb can be measured in both analyses, including theoretical and statistical uncertainties. We also show that the polarization of the top quark in W-gluon fusion can be detected at the Fermilab Tevatron and the CERN LHC.