Processes of inclusion and exclusion, of racialization of space and culturalization of debates, often involve conflicting discourses, narratives, and related identities about bordering, about access and rejection, and—more recently—about constructing new walls that are consistent with fundamental claims of critical discourse studies (CDS)—that is, that discourses and social realities are mutually constitutive and that discursive practices may have major ideological effects, helping to produce and reproduce unequal power relations and legitimize inclusion and exclusion, particularly in regard to ethnic and religious minorities, refugees, immigrants, and asylum seekers. In this chapter, I discuss the securitization and moralization of borders via specific discursive forms of argumentation and legitimation of exclusion, and then turn to one example: I briefly summarize Donald Trump’s argumentation for building a wall in order to keep Latin American (primarily Mexican) migrants out of the US. In the conclusion, I reflect on the resemiotization of discourses about exclusion via borders and walls, and their continuous reinforcement via a politics of fear.