Over the last fifteen years, undergraduate U.S. history courses have made great progress in incorporating primary sources and diverse voices into the survey. However, teachers still struggle to find professional writing by working historians in a format useful to undergraduates. Also, in 2014, the College Board redesigned the AP U.S. History curriculum and assessments to require students to demonstrate a critical approach to historical writing by professional historians. These facts have increased demand among teachers for access to high-quality secondary material by professional historians...