  We derive high-order threshold corrections for top quark production in
hadronic collisions from resummation calculations. We present analytical
expressions for the cross section through
next-to-next-to-next-to-next-to-leading order (N^4LO) and
next-to-next-to-leading logarithmic accuracy. Special attention is paid to the
role of subleading logarithms and how they relate to the convergence of the
perturbation series and differences between various resummation prescriptions.
It is shown that care must be taken to avoid unphysical terms in the
expansions. Numerical results are presented for top quark production at the
Tevatron. We find sizeable increases to the total cross section and
differential distributions and a dramatic reduction of the factorization scale
dependence relative to next-to-leading order.
