It stretches for 6 miles (9.7 km) south from Times Plaza, which is the triangle intersection created by Atlantic and Flatbush Avenues in Downtown Brooklyn, to Shore Road and the Belt Parkway in Bay Ridge.
Upon entering Sunset Park, Fourth Avenue passes under the Prospect Expressway (NY 27) and offers indirect access to it through local side streets.
The avenue continues to serve the automotive trade as far as the streets numbered in the low 40s, where it becomes flanked by large wall-to-wall apartment buildings.
[2] After crossing under the Gowanus Expressway viaduct into Bay Ridge, the arterial boulevard gives way to a four-lane street bordered by four- to five- story apartment buildings until it reaches Shore Road and the Belt Parkway under the Verrazano Narrows Bridge.
[6] In August 2019, following several cyclist deaths citywide, the NYCDOT announced that the remainder of Fourth Avenue between 38th and 60th Streets would receive protected bike lanes by late 2020.