Quoting from the Colonial North American Project at Harvard University,
This website provides access to some of the remarkable materials digitized as part of the ongoing, multi-year Colonial North American Project at Harvard University.
When complete, the project will make available to the world digitized images of all known archival and manuscript materials in the Harvard Library that relate to 17th and 18th century North America. Scattered through twelve repositories, these documents reveal a great deal about topics such as social life, education, trade, finance, politics, revolution, war, women, Native American life, slavery, science, medicine, and religion. In addition to reflecting the origins of the United States, the digitized materials also document aspects of life and work in Great Britain, France, Canada, the Caribbean, and Mexico. The ‘Essays’ on this website are the work of a Summer 2015 Arcadia Fellow, Alicia DeMaio, who was one of the first researchers to connect thematically related material from among the images digitized to date.The collection presently contains 5,136 manuscripts but it updated regularly. Here is a screenshot of the list of collections.
The images are in color and very high quality.
The supply of high quality original, digitized documents online seems to be endless.