Eastern Parkway follows the course of Jamaica Pass, a low area or valley resting between terminal moraines left here by the Wisconsin Glacier over two million years ago. During the Revolutionary War, Jamaica Pass provided British troops with access to American forces in what is now Prospect Park. This unfortunately contributed to the defeat of the Continental Army during the Battle of Long Island on August 27, 1776.
Eastern Parkway, the world's first parkway, was conceived by Frederick Law Olmsted and Calvert Vaux in 1866. The term parkway was coined by these designers as a landscaped road built expressly for "pleasure-riding and driving" or scenic access to Prospect Park (also designed by Olmsted and Vaux). The parkway was constructed from Grand Army Plaza to Ralph Avenue (the boundary of Brooklyn) between 1870 and 1874. Olmsted and Vaux intended Eastern Parkway to be the Brooklyn nucleus of an interconnected park and parkway system for the New York area. The plan was never completed but their idea of bringing the countryside into the city influenced the construction of major parks and parkways in cities throughout the United States.
The original design called for a 55-foot wide carriage drive centered between two pedestrian malls with four rows of trees extending 2.2 miles. There were also side roads for delivery wagons. Adorned almost exclusively with American Elms, this landscape of over 1100 trees is now mixed with twenty-four other species. Varieties of maple, linden, oak, and ash trees were introduced to discourage the spread of infestations such as Dutch Elm Disease. Eastern Parkway Extension, which proceeds northeast to Bushwick Avenue, continues the landscape for another two miles.
Eastern Parkway divided two communities: Crow Hill (now Crown Heights) to the south and Weeksville, an African-American settlement to the north. As real estate developers erected sumptuous apartment buildings that attracted professionals and their families to the area, the parkway became known as "Doctor's Row." A host of restrictions, starting before the turn of the century, protected the parkway and adjacent blocks. One regulation limited Anoxious or offensive" industrial and commercial development ranging from slaughterhouses to tanning plants, railways to gas stations. Another required that planting in yards along the parkway be approved to preserve the integrity of the design.
Full article on NYC Parks website