It's common to lose things while on the go accidentally. It is also typical to find lost stuff from streets, markets, malls, etc. This is especially prone to happen in cities like New York because of its peak hour rush.
Many may think they can keep it. Some others think they can leave it where they found it. But there is a rule specifying what to do if anyone finds lost things in New York. The New York Consolidated Laws, Personal Property Law - PEP § 252 states that -
“Any person who finds lost property of the value of twenty dollars or more or comes into possession of property of the value of twenty dollars or more with the knowledge that it is lost property or found property shall, within ten days after the finding or acquisition of possession thereof, either return it to the owner or report such finding or acquisition of possession and deposit such property in a police station or police headquarters of the city where the finding occurred or possession was acquired, but if the finding occurred or possession was acquired in buildings or on grounds or premises under the control and supervision of the commissioner of general services as described in article two of the public buildings law, then the property may also be deposited in a station of the capital buildings police.”
In simple words, the law says that if you find lost property worth more than 20 dollars or 20 dollars (or more) money, you should return it to the owner within ten days of finding it. If you don’t know the owner’s identity, you should hand it over to the police. In case you find it outside the city, return it to the state police, sheriff, or the state park police. Also, you can return it to the owner of the place you found it.
Non-compliance with this law can lead to you being charged with a misdemeanor and, if convicted, can be punished by a fine of one hundred dollars (or less) or six months of imprisonment (or less), or both.