A "paper street" usually occurs when a road or street shown on a developer's plan of homes, isn't officially accepted by the municipality. Possibly, the developer never laid out or paved the road to borough specifications or perhaps, the road was never paved at all and was only a proposed road for the plan of homes, which may or may not have been built.
Another way a "paper street" may occur is when a proposed road isn't used by the public for 21 years. The 21-year period of using or accepting the roadway is a statute of limitations. After 21 years, a municipality is prohibited from accepting a "paper street" and the property automatically reverts back to the abutting property owners. Because "paper streets" automatically revert back after 21 years, many people don't even know that they may own up to one-half of the "paper street" beside or behind their homes.
Even if the borough doesn't formally adopt a "paper street," the "street" may still become an official borough road if the borough paves and maintains it. In this instance, an implied acceptance occurs, and the road is no longer a "paper street."
Most "paper streets" have been in existence for many years and may be fifty, eighty or even one hundred years old. However, because most municipalities have enacted subdivision ordinances, "paper streets" usually don't occur anymore.