There is very limited theory and policy guidance that specifically relates to multijurisdictional and multimodal (M&;M) infrastructure corridors: those that traverse national boundaries and encompass multiple modes of co-located infrastructure modes. This paper develops a framework for understanding the social welfare costs and benefits—and the barriers to implementing—these corridors. The framework posits the need for both a dedicated assembler and a national (or supranational) sponsor. An assembler provides the platform to match up initial property rights holders, infrastructure mode providers and end users. The sponsor financially and politically backstops an assembler. We decompose the economic necessity for, and advantages of, an assembler and also those that result from some degree of multimodality. We also consider the economic and political barriers to M&;M corridor implementation. To illustrate these, we review the evidence from the very small number of proposed or realised M&;M corridors and closely related projects. Although reliable evidence is scarce, it is consistent with the framework’s implications regarding the need for both an assembler and a sponsor.