A group trying to bring attention to an African burial ground in Portsmouth, N.H., has been approved to receive a $20,000 grant from the National Endowment for the Arts to help create a memorial park. Archaeologists and historians believe the remains of at least 200 people could be buried beneath Chestnut and State streets. The graves were discovered by construction workers in 2003. It is believed that African slaves or free Africans were buried in the area from 1705 until the 1790s. A formal committee of residents and city representatives was created to explore ideas to commemorate the site. The plan is to create a memorial on Chestnut Street.