Here's an excerpt of the text of the NYS Penal Law that deals with trespass, with the relevant items in bold and italics. From my interpretation, as long as the land is NEITHER FENCED NOR POSTED, and you don't know otherwise, you can legally enter upon it given that it is "unimproved or unused." Should the landowner greet you with a 12 gauge, you will then "know otherwise," and should get off the land immediately. The trickier part is defining the contsraints of the terms "unimproved" and "unused."
Source:
http://wings.buffalo.edu/law/bclc/web/N ... htm#art140
TITLE I--OFFENSES INVOLVING DAMAGE TO AND INTRUSION UPON PROPERTY
ARTICLE 140--BURGLARY AND RELATED OFFENSES
Section 140.00 Criminal trespass and burglary; definitions of terms
The following definitions are applicable to this article:
1. "Premises" includes the term "building," as defined herein, and any real property.
2. "Building," in addition to its ordinary meaning, includes any structure, vehicle or watercraft used for overnight lodging of persons, or used by persons for carrying on business therein, or used as an elementary or secondary school, or an inclosed motor truck, or an inclosed motor truck trailer. Where a building consists of two or more units separately secured or occupied, each unit shall be deemed both a separate building in itself and a part of the main building.
3. "Dwelling" means a building which is usually occupied by a person lodging therein at night.
4. "Night" means the period between thirty minutes after sunset and thirty minutes before sunrise.
5. "Enter or remain unlawfully." A person "enters or remains unlawfully" in or upon premises when he is not licensed or privileged to do so. A person who, regardless of his intent, enters or remains in or upon premises which are at the time open to the public does so with license and privilege unless he defies a lawful order not to enter or remain, personally communicated to him by the owner of such premises or other authorized person. A license or privilege to enter or remain in a building which is only partly open to the public is not a license or privilege to enter or remain in that part of the building which is not open to the public.
A person who enters or remains upon unimproved and apparently unused land, which is neither fenced nor otherwise enclosed in a manner designed to exclude intruders, does so with license and privilege unless notice against trespass is personally communicated to him by the owner of such land or other authorized person, or unless such notice is given by posting in a conspicuous manner. A person who enters or remains in or about a school building without written permission from someone authorized to issue such permission or without a legitimate reason which includes a relationship involving custody of or responsibility for a pupil or student enrolled in the school or without legitimate business or a purpose relating to the operation of the school does so without license and privilege.
Section 140.05 Trespass
A person is guilty of trespass when he knowingly enters or remains unlawfully in or upon premises.
Trespass is a violation.
Section 140.10 Criminal trespass in the third degree.
A person is guilty of criminal trespass in the third degree when he knowingly enters or remains unlawfully in a building or upon real property
(a) which is fenced or otherwise enclosed in a manner designed to exclude intruders; or
(b) where the building is utilized as an elementary or secondary school or a children's overnight camp as defined in section one thousand three hundred ninety-two of the public health law or a summer day camp as defined in section one thousand three hundred ninety-two of the public health law in violation of conspicuously posted rules or regulations governing entry and use thereof; or
(c) located within a city with a population in excess of one million and where the building or real property is utilized as an elementary or secondary school in violation of a personally communicated request to leave the premises from a principal, custodian or other person in charge thereof; or
(d) located outside of a city with a population in excess of one million and where the building or real property is utilized as an elementary or secondary school in violation of a personally communicated request to leave the premises from a principal, custodian, school board member or trustee, or other person in charge thereof; or
(e) where the building is used as a public housing project in violation of conspicuously posted rules or regulations governing entry and use thereof; or
(f) where a building is used as a public housing project in violation of a personally communicated request to leave the premises from a housing police officer or other person in charge thereof; or
(g) where the property consists of a right-of-way or yard of a railroad or rapid transit railroad which has been designated and conspicuously posted as a no-trespass railroad zone, pursuant to section eighty-three-b of the railroad law, by the city or county in which such property is located.
Criminal trespass in the third degree is a class B misdemeanor.
spec