Historian Donald Yacovone discovered a collection of 3,000 old textbooks that consistently ignored the achievements of non-white Americans while portraying African Americans as incapable of learning. These books, some used as late as the 1940s and beyond, contained tropes about enslaved people that were reinforced by the outsized influence of Texas and California on the publishing industry. The damage from these educational materials is described as a "tough lesson to unlearn."