Many streets in New York have alternate side regulations, which allow for street cleaning. Most alternate side parking signs are clearly marked with signs featuring a “P” crossed by a broom. Some areas have three-hour restrictions (e.g. 8 am to 11 am) but times vary considerably.
The City suspends alternate side parking rules on the legal and religious holidays listed below, and makes emergency suspensions because of severe weather or other emergencies. (more info)