Olson, Shayla F. 2019. State Networks Database v.1.1. East Lansing, MI: Institute for Public Policy and Social Research (IPPSR).
The State Networks dataset is a compilation of many state-to-state relational variables, including measures of shared borders, travel and trade between states, and demographic characteristics of state populations. The 2,550 units in the dataset are dyadic state-pairs (e.g., Alabama–Alaska, Alabama–Arizona, Alabama–Arkansas, and so on, for each state plus the District of Columbia). Read my blog post that introduces this data here: Michigan Policy Wonk Blog: Midwest Relations.