15 July 1905, New York Times, pg. 1:
Over "San Juan Hill" and "The Gut" early last night there was a race riot which terrorized the neighborhood for an hour, sent several persons to the hospital, and made it necessary to call the reserves from six police stations. "San Juan Hill" is where Amsterdam Avenue rises to a point at Sixty-second Street; "The Gut" is the same street where it runs down to West End Avenue.
The police of the West Sixty-eighth Street Station expect at least one small riot on the Hill or in The Gut each week. But last night's came one day before the usual times, and it was more severe than any other racial disturbance for two or three years.
East of Amsterdam Avenue live mostly white people; west of Amsterdam Avenue live mostly negroes. The feeling between the two is always hostile. It comes out on this borderland.