The White House Office of Science & Technology Policy says that publicly-funded research shall be made available to the public. So, both the publications and data generated by research funded by any federal grant will be "open access".
This is policy is developing. Researchers have time to learn what is required when applying for grants or for papers and data created through them.
See also the Libraries' Scholarly Communications group.
The Morrill Act of 1862 established new public institutions in each state through the grant of federal lands. These new institutions began teaching agriculture as a liberal, practical education with direct relevance to daily life.
That tradition lives on to this day.
To read more about what a Land Grant university is, see this FAQ.