We modify an approach of Johnson to define the distance of a bridge splitting of a knot K in a 3-manifold M using the dual curve complex and pants complex of the bridge surface. This distance can be used to determine a complexity, which becomes constant after a sufficient number of stabilizations and perturbations, yielding an invariant of (M, K). We also give evidence toward the relationship between the pants distance of a bridge splitting and the hyperbolic volume of the exterior of K. Mathematics Subject Classification 57M25, 57M27, 57M50 (primary). 44 ALEXANDER ZUPAN Theorem 1.1. Let K be a knot in a closed, orientable 3-manifold M, where M has no S 2 × S 1 summands, let Σ be a splitting surface for (M, K), and let Σ h c be an (h, c)-stabilization of Σ. Then the limits lim h,c→∞ B(Σ) and lim h,c→∞ B P (Σ) exist. Moreover, they do not depend on Σ and thus define invariants B(M, K) and B P (M, K) of the pair (M, K).The pants complex P (Σ) of a surface Σ is itself an interesting object of study; for instance, Brock has shown that it is quasi-isometric to the Teichmüller space T (Σ) equipped with the Weil-Petersson metric [2], and Souto has revealed other surprising connections between pants distance and the geometry of certain 3-manifolds [23]. We exploit a theorem of Guéritaud and Futer [3] to prove the following theorem.Theorem 1.2. Suppose that K is a hyperbolic 2-bridge knot, Σ is a (0, 2)-splitting surface for K, v 3 is the volume of a regular ideal tetrahedron, and v 8 is the volume of a regular ideal octahedron. ThenThe paper proceeds in the following manner: in Section 2, we provide background information and include a proof of the analog of the Reidemeister-Singer theorem for bridge splittings in arbitrary manifolds. In Section 3, we introduce the curve, dual-curve, and pants complexes, and in Section 4 we define the distance of a bridge splitting and prove several basic facts about this distance. In Section 5, we use the distance of the previous section to define bridge and pants complexity, and prove the main theorem. In Section 6, we demonstrate several properties of these new invariants and, in Section 7, we define the concept of a critical splitting to provide explicit calculations in Section 8. Finally, in Section 9, we discuss connections between pants distance and hyperbolic volume, and in Section 10 we include several interesting open questions.