Where Is String Theory in the Space of Scattering Amplitudes?

We use the S-matrix bootstrap to carve out the space of unitary, crossing symmetric and supersymmetric graviton scattering amplitudes in ten dimensions. We focus on the leading Wilson coefficient a controlling the leading correction to maximal supergravity. The negative region alpha < 0 is excluded by a simple dual argument based on linearized unitarity (the desert). Awhole semi-infinite region alpha greater than or similar to 0.14 is allowed by the primal bootstrap (the garden). A finite intermediate region is excluded by nonperturbative unitarity (the swamp). Remarkably, string theory seems to cover all (or at least almost all) the garden from very large positive a-at weak coupling-to the swamp boundary-at strong coupling.