Roads may contribute to the spread of plant invasions by acting as corridors for seed movement, as well as habitat for nonnative plant species, but seed dispersal and seedling establishment are largely unexplored along large, paved roads. We collected one season of seed rain and quantified co-occurring vegetation at multiple distances from the road along an interstate highway. Nonnative seed species richness decreased with distance from the road. Distance did not significantly affect native species seed measures. Furthermore, 33% of nonnative species found in the seed rain were not present in the vegetation. These results suggest that the Interstate aids dispersal of nonnative seeds. Seeds of 58% of the native and nonnative species found in the seed rain were not present in the vegetation, indicating that at least some of these species are unable to establish along the road. Independent of distance from the road, more nonnative and less native vegetation was found in areas of higher soil pH, suggesting that pH may limit the establishment of native species in the road verge. The role of soil variables, including pH, in seedling establishment along roads warrants further investigation.