||The San Francisco art and architecture collective Ant Farm built Cadillac Ranch in 1974 outside of Amarillo, Texas, to showcase "the rise and fall of the Cadillac tailfin." The ten vintage Cadillacs buried nose‐first in a row along the old Route 66, with their tailfins jutting up obliquely, is often read as a monument to the golden era of the American automobile. Yet despite (and because of) its continued popularity, the work has rarely been taken seriously as art. This thesis proposes a revaluation of Ant Farm's iconic project, and represents an attempt to position Cadillac Ranch as an important sculptural installation that speaks to many of the key concerns of the American avant‐garde of the 1960s and 1970s. My title references the Jewish Museum's 1966 exhibition "Primary Structures: Younger American and British Sculpture," which sparked the rapid legitimization of minimalist sculpture in the postwar American art world. Reading Cadillac Ranch against this seminal artistic tradition, I argue that the project can be read as a monumental epitaph to the exhausted aesthetic models and sociopolitical narratives of the late‐modern period. Cadillac Ranch memorializes modernism by rehearsing its formal techniques, but as a hybridized, participatory project, it also enacts modernism's end.