The initial reason for the Bear Mountain Parkway was to connect the Taconic State Parkway (or then, the Bronx River Parkway Extension), to the Bear Mountain Bridge. At that time, the Tappan Zee Bridge had not been constructed, and the Bear Mountain Bridge was an extremely important crossing of the Hudson River for Westchester, Rockland, Putnam, and Orange County residents. Today, due to the popularity of the Tappan Zee, and the traffic issues caused by the two-lane roads descending to the Bear Mountain Bridge, the bridge is not a popular Hudson River crossing, and consequently, the Bear Mountain Parkway was never finished. Talks of its completion resurfaced in 2000, but because the Yorktown area is much more populated than it was in the 1930s, its completion seems nearly impossible.
In Cortlandt, the parkway interchanges with US 6 and meets several surface roads ahead of an intersection with US 202 and NY 35. Here, the Bear Mountain Parkway merges with the two-lane US 202 and NY 35, creating a physical concurrency extending eastward into neighboring Yorktown. Roughly one mile from the town line, the parkway separates from US 202/NY 35 and progresses to the northeast as a four-lane undivided roadway. After a short distance, the parkway becomes separated by a median prior to merging with the southbound Taconic State Parkway. The northbound Taconic is accessed by way of US 202/NY 35.
NY 987H, the internal NYSDOT designation for the parkway, terminates at both ends of the physical overlap with US 202/NY 35 and applies only to the segments of the road separate from US 202/NY 35.
In 1941 the Taconic State Park Commission assumed control of the Bronx River extension, and then combined the section between the Bronx River Parkway and the, as it was known then, Eastern State Parkway to create the Taconic State Parkway. The section between the Taconic and Annsville then received the name of Bear Mountain State Parkway.
In 2000, there was an initiative to complete the final missing piece of the Bear Mountain Parkway. Although, most if not all the right-of-way, has already been acquired, the issue not overcome was whether to allow trucks on the parkway.