There are 9 US Post Offices in Garrett County serving a total of 27,932 residents equating to 3,104 residents per post office. It's estimated that approximately 44,583 packages are handled across the 9 county post offices annually. Garrett County (g\u0259r\u025bt) is the westernmost county of the U.S. state of Maryland. As of the 2010 census, the population was 30,097, making it the third-least populous county in Maryland. Its county seat is Oakland. The county was named for John Work Garrett (1820\u20131884), president of the Baltimore and Ohio Railroad. Created from Allegany County, Maryland in 1872, it was the last Maryland county to be formed. Garrett County has long been part of the media market of Pittsburgh, Pennsylvania. It is considered to be a part of Western Maryland. The Commonwealth of Pennsylvania is to the north. The Maryland\u2013Pennsylvania boundary was surveyed and marked between April 1765 and October 1767 by astronomer Charles Mason and surveyor Jeremiah Dixon. This boundary is commonly known as the Mason\u2013Dixon line. The eastern border with Allegany County was defined by the Bauer Report, submitted to Governor Lloyd Lowndes, Jr. on November 9, 1898. The Potomac River and State of West Virginia lie to the south and west. Garrett County lies in the Allegheny Mountains, which here form the western flank of the Appalachian Mountain Range. Hoye-Crest, a summit along Backbone Mountain, is the highest point in Maryland. The Eastern Continental Divide runs along portions of Backbone Mountain. The western part of the county, drained by the Youghiogheny River, is the only part of Maryland within the Mississippi River drainage basin. All other parts of the county are in the Chesapeake Bay basin. Garrett County contains over 76,000 acres (310 km2) of parks, lakes, and publicly accessible forestland. Popular activities in the county include camping, hiking, backpacking, rock climbing, alpine and cross county skiing, snowmobiling, hunting, ice fishing, fly fishing, whitewater canoeing, kayaking, rafting, boating, swimming, sailing, horseback riding, and water skiing. The National Register of Historic Places listings in Garrett County, Maryland has 20 National Register of Historic Places properties and districts, including Casselman Bridge, National Road a National Historic Landmark. Garrett County is part of Maryland's 6th congressional district. The extreme south of the county lies within the United States National Radio Quiet Zone."