Effective EVPA swing location ﹩({\tilde{R}}_{{\rm{face}}-{\rm{on}}})﹩ as a function of both spin (left panel) and terminal Lorentz factor (right panel) for a sample jet. Analytic solutions exist in the nonrelativistic (γ_∞ ∼ 1) regime and the force-free (γ_∞ ≫ 1) regime, which are shown as blacked dashed lines in the left panel. These two analytic solutions can then be stitched together using Equation (24), which is overplotted as black dashed lines in the right panel. In all cases, ﹩{\tilde{R}}_{{\rm{face}}-{\rm{on}}}﹩ depends strongly on black hole spin and γ_∞.