OPR meaning in General ?

The Boston Post Road was a system of mail-delivery routes between New York City and Boston, Massachusetts that evolved into one of the first major highways in the United States.

The three major alignments were the Lower Post Road (now U.S. Route 1 (US 1) along the shore via Providence, Rhode Island), the Upper Post Road (now US 5 and US 20 from New Haven, Connecticut by way of Springfield, Massachusetts), and the Middle Post Road (which diverged from the Upper Road in Hartford, Connecticut and ran northeastward to Boston via Pomfret, Connecticut).

In some towns, the area near the Boston Post Road has been placed on the National Register of Historic Places, since it was often the first road in the area, and some buildings of historical significance were built along it. The Boston Post Road Historic District, including part of the road in Rye, New York, has been designated a National Historic Landmark. The Post Road is also famous for milestones that date from the 18th century, many of which survive to this day. In parts of Connecticut (generally east of Hartford), it is also known as Route 6.