Historical land use has shaped ecosystem structure and function in much of eastern North America, but the question of how long the legacies of 19^th and 20^th century agriculture will persist in forested landscapes remains a matter of debate. To evaluate whether the legacies of land use are diminishing over time we resampled permanent vegetation plots in areas which either did or did not have an agricultural history. This study focused on changes in trees, shrubs, herbaceous plants, and soil chemistry between 1984 and 2006 at the Cary Institute of Ecosystem Studies in southeastern New York State.  Substantial shifts in tree species composition were observed, including a decline in the basal area of Cornus florida and Quercus prinus. These changes appear to be due, respectively, to dogwood anthracnose and mortality associated with gypsy moth (Lymantria dispar) defoliation. Quercus rubra and Acer saccharum increased in basal area over the same period. Sapling density in the plots remained nearly constant between 1984 and 2006, but seedling density nearly doubled. The invasive herbaceous plant Alliaria petiolata increased markedly in percent cover and frequency of occurrence. Acer rubrum and Q. prinus tree abundances were highly correlated with land use history, while A. saccharum and Q. rubra were not, so the documented changes in forest composition have obscured some of the legacies of land use history on this forest over the past two decades. In addition to the changes caused by novel pests and pathogens, we show how other regional influences on forests (such as fire suppression and invasive plants) may diminish the differences in forest composition between forests with and without agricultural history.