Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Countries gain and lose territories over time, generating territory flows that represent the transfer of territorial sovereignty. Countries also export and import goods, creating trade flows that represent the transfer of merchandise ownership. We find a substitution between these two international flows during the years 1870 and 2008; that is, country pairs with greater trade flows have smaller territory flows. This indicates how international trade enhances international security: reciprocal goods transactions discourage irreciprocal territorial exchanges.