Harvard just made accessible a searchable online database of close to 3500 antislavery and antisegregation petitions sent to the Massachusetts colonial and state legislatures from the 1600s to 1870. These petitions are housed at the Massachusetts Archives.
A small taste:
Each petition image is annotated with detailed information, and the dataset provides web-based browsing, searching, and filtering, along with images of the digitized documents. These digitized images include documents that date back to antislavery efforts from 1649 but also reflect black Revolutionary War veterans, female abolitionists (including Sojourner Truth), and petitions submitted before, during, and after the Civil War. The images, and the associated metadata, will be distributed by the Harvard Dataverse Network infrastructure and will be made publicly available for the first time at this event on February 27, 2015, at the end of Black History Month.