Below 148th, St. Nicholas returns to a rough alignment with the grid, with Convent Avenue one block west and Edgecombe Avenue to the east, down to 124th Street. Below 124th, St. Nicholas Avenue takes a sharp diagonal, crossing Frederick Douglass Boulevard at 121st Street, and Adam Clayton Powell Jr. Boulevard at 116th Street, ending at Lenox Avenue, just north of Central Park. Its 17th-century origin as part of the Eastern Post Road accounts for its non-conformance to the grid pattern proposed by the Commissioners' Plan of 1811.
St. Nicholas Avenue deviates from the grid below 148th Street, aligning with Convent Avenue to the west and Edgecombe Avenue to the east until it reaches 124th Street. Below this point, St. Nicholas Avenue takes a sharp diagonal turn, intersecting Frederick Douglass Boulevard at 121st Street and Adam Clayton Powell Jr. Boulevard at 116th Street before terminating at Lenox Avenue near Central Park.