This article assesses the relationship between the imposed Central African Federation (1953–63) and the ways in which East and Central African thinkers and leaders conveyed and pursued the possibilities of decolonization. Existing literature on federalism in twentieth-century Africa fails to place regional projects in dialogue, studying in isolation East Africa and Central Africa, ‘utopian’ and oppressive regionalisms. But such clear dividing lines were not articulated in the four discursive ‘sketches’ of East and Central Africa that this article brings to light: those of anti-Federation organizations in Nairobi and Ndola in 1952; students at Makerere College (Kampala) in 1953; mobile Malawian activists in regional and pan-African forums around 1955–8; and East African party publicity representatives around 1958–60. At each of these critical moments, thinkers creatively constructed various relationships between geographical space and chronological change, through the lens of a broader, interdependent East and Central Africa, as a means to fend off perceived threats to a precarious advancement towards a democratic future. Attending to the evolution of these ideas shows not only how the Central African Federation placed material constraints on regional solidarity, but how ‘thinking regionally’ could support the case for national borders, even before decolonization.