Drawing on recent work on the nature of the numbering system of the Tractatus and Wittgenstein’s use of that system in his composition of the Prototractatus, the paper sets out the rationale for the online tool called The University of Iowa Tractatus Map. The map consists of a website with a front page that links to two separate subway-style maps of the hypertextual numbering system Wittgenstein used in his Tractatus. One map displays the structure of the published Tractatus; the other lays out the structure of the Prototractatus. The site makes available the full text of the German and the two canonical English translations. While we envisage the map as a tool that we would like a wide variety of readers to find helpful, we argue that our website amounts to a radically new edition of Wittgenstein’s early masterpiece, with far-reaching implications for the interpretation of that text. In particular, we claim that our visually compelling presentation of the book’s overall structure delivers on Wittgenstein’s cryptic claim in a letter to his publisher that it is the numbers that “make the book surveyable and clear”.