A steady-state model of crust production and destruction for the past 180 m.y. was proposed by B. Parsons and advocated by D. Rowley. Such a model has serious implications for models of secular variations in, e.g., global sea level, global climate, and seawater chemistry. This paper presents an analysis of the steady-state model and then offers alternative extensions of that model that allow for non–steady-state production of ocean crust with time. Results suggest that the observed linear decrease in area versus age of ocean floor does not force a steady-state view of seafloor spreading.