Contiguous property ownership is relevant when one property owner can negatively impact or infringe upon the rights of an adjacent property owner. Examples of negative impact or infringement can include how someone wants to build on their property (building of a subdivision, hotel, theme park or animal refuge). Also relevant would be the use of chemicals and pesticides if the property was farm related.
Contiguous property owners should extend good faith efforts to notify other owners of any change or construction that could bear negative impact. For example, if a land owner decides to build a subdivision on his piece of property, he would likely send a certified letter to all of the contiguous property owners to advise them of his intent. He would do this because the development could have an impact on the property values of the other adjacent owners.
Certain state laws modify the definition of contiguity. For example, in South Carolina, contiguous property is not null if the property is separated by a body of water or a marshland. However, most states require that properties be in actual contact in order to be deemed contiguous.