Near-threshold fatigue crack growth behavior has been analyzed for a broad selection of steels surveyed from the literature. It is clear first of all that apparent values of the threshold stress-intensity factor (ΔK_th) can vary widely, roughly an order of magnitude. Though in many instances actual ΔK_th values are difficult to define rigorously, a pronounced transition point or “knee” is apparent in the near-threshold region of the conventional logarithmic plot of fatigue crack growth rate (da/dN) as a function of stress-intensity range (ΔK). Though the values of ΔK associated with these transition points (ΔK_T) for an individual steel may tend to exhibit a functional dependence on yield strength (σ_ys) or grain size (¯ℓ)—as is the case, for example, with a low-carbon ferritic steel—it is unmistakably clear that for the gamut of steels examined (15 cases), the transition points do not order on the basis of either σ_ys or ¯ℓ alone. Rather, values of ΔK_T for the gamut of steels order on the basis of a synergetic interaction of σ_ys and ¯ℓ, according to the equation, ΔKT=5.5σysℓ¯. This relationship was derived in the cyclic plastic zone model of fatigue crack growth established in our prior work with titanium alloys. In further agreement with this model, ΔK_T has been identified for these steels as the point at which the cyclic plastic zone attains the mean grain size. The significance and implications of these findings appear far-reaching, as the steels surveyed include those of both high and low strength, a wide range of effective grain sizes (mean free path in the case of high-strength steel), and a host of microstructural types (ferritic, martensitic, pearlitic, bainitic, and austenitic).