Ok, so I have a little history book published by the Folsom Historical Society, "Images of America, Folsom, Ca." I see reference (p. 61) that the name "Negro Bar" has been around at least since 1851 when Father Ingoldsby conducted church services there. On page 56, there is a picture of the Picker building, now under Folsom Lake, but previously located on Mormon Island. It says, "other towns that once thrived in this area were known by these colorful names: Jenny Lind Flat, Negro Hill, Condemned Bar, Elephant Flat, Rattlesnake Bar, Red Bank, Maple Ridge, Poker Bar and Salmon Falls."
It sounds like Negro Bar was not very big, per the Folsom History Museum, it was "little more than a cluster of tents and shacks." According to other sources ( http://files.usgwarchives.net/ca/eldorado/cemeteries/mormon-island.txt ) the graves were taken from a variety of cemeteries.
actually Negro Bar, which was located just below the corporation yard here in Folsom was about two blocks long and included many framed buildings, including at least two two-story buildings. There were hotels, stores, a doctor, etc. It existed from 1849 to 1855, when the whole town relocated up to what is now the Sutter Street area after the arrival of the railroad.
Negro Hill and "N-word" Hill were located in the area now inundated by Folsom Lake. And it was during the gold rush known by the N-word. There was even a ditch with the same name. So it is an accurate historic word, even if it is offensive.