Adjoining landowners are owners of land with common boundaries, and have mutual rights, duties, and obligations related to their adjoining pieces of land.

In North Dakota, adjoining landowners, also known as adjacent or contiguous property owners, have certain rights and responsibilities concerning their shared property boundaries. These rights and duties are often governed by state statutes and common law. For instance, landowners have the duty to use their property without causing harm to their neighbors' land. This includes proper management of water runoff, not creating a nuisance, and maintaining boundary fences in certain cases. North Dakota Century Code (NDCC) may contain specific provisions regarding fence maintenance and other boundary issues, such as NDCC 47-26 which deals with partition fences and the obligations of landowners to maintain them. Additionally, landowners have the right to trim branches or roots that encroach onto their property from a neighbor's tree, but they must do so without unnecessarily harming the neighbor's tree. Disputes over property lines or encroachments may be resolved through legal action, and in some cases, the doctrine of adverse possession may apply if one landowner has occupied a portion of the adjoining landowner's property for a sufficient period under certain conditions. It is advisable for landowners to consult with an attorney to understand the full scope of their rights and obligations in relation to adjoining properties.