Effective theories for the thermal Wilson line are constructed in an SU(N)
gauge theory at nonzero temperature. I propose that the order of the deconf
ining phase transition for Z(N) Wilson lines is governed by the behavior of
SU(N) Wilson lines. In a mean field theory, the free energy in the deconfi
ned phase is controlled by the condensate for Z(N) Wilson lines. Numerical
simulations on the lattice, and the mean held theory for Z(3) Wilson lines,
suggest that about any finite temperature transition in QCD the dominant c
orrelation length increases by a large, uniform factor, of order five.