  Drell-Yan lepton pairs produced in the process $p \bar{p} \rightarrow
\ell^+\ell^- + X$ through an intermediate $\gamma^*/Z$ boson have an asymmetry
in their angular distribution related to the spontaneous symmetry breaking of
the electroweak force and the associated mixing of its neutral gauge bosons.
The CDF and D0 experiments have measured the effective-leptonic electroweak
mixing parameter $\sin^2\theta^{\rm lept}_{\rm eff}$ using electron and muon
pairs selected from the full Tevatron proton-antiproton data sets collected in
2001-2011, corresponding to 9-10 fb$^{-1}$ of integrated luminosity. The
combination of these measurements yields the most precise result from hadron
colliders, $\sin^2 \theta^{\rm lept}_{\rm eff} = 0.23148 \pm 0.00033$. This
result is consistent with, and approaches in precision, the best measurements
from electron-positron colliders. The standard model inference of the on-shell
electroweak mixing parameter $\sin^2\theta_W$, or equivalently the $W$-boson
mass $M_W$, using the \textsc{zfitter} software package yields $\sin^2 \theta_W
= 0.22324 \pm 0.00033$ or equivalently, $M_W = 80.367 \pm 0.017 \;{\rm
GeV}/c^2$.
