New York Laws
Article 34 - Operation of Bicycles and Play Devices
1237 - Method of Giving Hand and Arm Signals by Bicyclists.

ยง 1237. Method of giving hand and arm signals by bicyclists. All
signals herein required to be given by bicyclists by hand and arm shall
be given in the following manner and such signals shall indicate as
follows:

1. Left turn. Left hand and arm extended horizontally.

2. Right turn. Left hand and arm extended upward or right hand and arm
extended horizontally.

3. Stop or decrease speed. Left hand and arm extended downward.