This paper examines how transmission coordinates with generation to the long term in a liberalized power system. We rely on a modular analysis to separate the mechanisms of coordination between generation and transmission of electricity into distinct modules. The governance structure of transmission completes this analysis framework. We then show that in a logic of complementarity, this governance structure influences the options that TSO implements to manage effectively power flows. Although locational signals are necessary to guide the installation of new power plants, the governance structure explains that investment in network may be the only effective method of longterm coordination between generation and transmission.