The standard model for the field-induced spin-density-wave (FISDW) transitions in the Bechgaard salts (TMTSF${)}_{2}$X, where TMTSF is tetramethyltetraselenafulvalene, explains a cascade of phase trasitions with each phase associated with the quantum Hall effect. The ${\mathrm{ClO}}_{4}$ salt is sufficiently different that it has inspired a series of theoretical modifications from the standard model. To test these models we have performed simultaneous ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{x}}$, ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{y}}$, specific-heat, magnetocaloric effect, and magnetization measurements in the field range from 0--9 T. We find that all of the transport transitions, specifically the Hall resistance jumps, are associated with thermodynamic transitions. We observe the emergence of a new FISDW state characterized by a distinct Hall plateau. It arises from what was originally believed to be a tetracritical point in the phase diagram. We find no evidence for an arborescent phase diagram, but rather the signature of a single pairwise splitting of the phase boundaries. The higher-field transitions are decidedly first order, hysteretic, and ``lossy.'' Anion disorder decreases the number of observed phases and shifts the transition fields.