From the DPLA:
Digital Public Library of America (DPLA) is very pleased to announce the release of its second group of Primary Source Sets about topics in US history, literature, and culture, along with new features for navigating our growing project.
These sets were developed and reviewed by our Education Advisory Committee for use by students and teachers in grades 6-12 and higher education. Each set includes an overview, ten to fifteen primary sources, links to additional resources, and a teaching guide. This project was generously funded by the Whiting Foundation.
Direct to ALL Primary Source Sets
Direct to Some Recently Added Primary Source Sets