Vector-borne diseases (VBD) pose a major concern for public health worldwide. Identifying putative vectors and their potential contribution to transmission is a crucial step in understanding vector-borne disease hazard. However, existing metrics are limited in their utility to inform transmission hazard in zoonotic multi-vector, multi-host VBD systems. We present the Vector Potential Index (VPI), a novel metric for evaluating and comparing the potential of blood-feeding arthropod vectors to contribute to zoonotic VBD transmission. Taking a meta-analysis approach, the VPI combines vector competence and host use data obtained from scientific literature to assign relative and absolute VPI ranks across species and transmission cycles. Using West Nile virus (WNV) in the eastern United States as a model system, our results demonstrate the ability of VPI to provide a representative assessment of vector species' potential contribution to transmission hazard in the epizootic and enzootic transmission cycles. Most species had low vector potential, and although Aedes species were the most competent WNV vectors in the laboratory, only Culex species were assigned higher VPI ranks. Additionally, the VPI suggests that the contribution of Culex salinarius to WNV transmission in the U.S. may be greater than previously assumed based on assessments of individual parameters. Relative and absolute VPI ranks assigned to species aligned with recent work reviewing their role as vectors in the transmission cycles, indicating that by jointly considering vector competence and host use, the VPI effectively quantifies the species-specific potential to contribute to WNV transmission hazard in the natural environment, using existing data. We propose the objective and reproducible VPI as a powerful yet simple tool for scientists and public health practitioners, where this trait-based approach has considerable potential to provide new insights into disease systems and enhance VBD surveillance and intervention strategies.