<p>Annual grass invasion is a major threat to sagebrush steppe ecosystems. While environmental factors such as wildfire, elevation, and climate are known to shape annual grass invasion at broad scales, heterogeneity in distributions could result from species differences or interactions with grazing. Here we conducted an extensive field survey of grazed public lands across the Northern Great Basin. We sampled plant species cover, soil texture, cattle dung counts, and topography, in plots stratified at the pasture level by fire history and within pastures by aspect and distance to water. The most common invasive annual grass, cheatgrass, occurred ubiquitously despite fire history, elevation, or climate, and was most abundant at warmer locations both regionally and locally. Three other annual grasses–Japanese brome, medusahead, and ventenata–often diverged from cheatgrass (and one another) in regional and local responses. In contrast to cheatgrass, Japanese brome had higher cover at cooler sites regionally and decreased with grazing intensity locally. Medusahead responded oppositely to local grazing gradients, with higher cover near water where grazing tended to be heaviest. Both Japanese brome and medusahead had higher cover in burned areas, while a weaker relationship of cheatgrass to fire could reflect its late stage of invasion. Overall, results show that species-specific environmental responses may contribute to expansion of annual grasses into new environments, that high local grazing intensity may enhance expansion of some species while mitigating others, and that environmental drivers may be most predictive of spread mid-invasion, before a species has become ubiquitous.</p>