The view from the summit of Sugarloaf in T5 R7 WELS looks out over the Katahdin Woods and Waters National Monument. Carey Kish photo

Tunk Mountain rises just north of Route 182 in a place called T10 SD, halfway between the Downeast towns of Franklin and Cherryfield. The extensive cliffs and ledges as well as a handful of ponds at its southeastern base – all part of the 15,479-acre Donnell Pond Public Lands – may be explored on a 5-mile system of foot trails.

On a recent hike at Tunk, I thought a lot about the oddly-named T10 SD, plus the many other alphanumeric township names around eastern and northern Maine, head-scratchers like T4 R8 WELS, T3 R4 BKP WKP and T2 R8 NWP. They’re all part of Maine’s unorganized territories of 429 townships, and lacking any organized local government, they’re administered directly by a variety of state agencies. T is for township and R stands for range, that much I also knew, but what do the rest of these strange acronyms mean and what’s their origin?

There are hundreds of hikes in Maine’s 10.4 million acres of unorganized townships and I figured it would be nice to know a little more history about these remote places. Home again from Tunk Mountain, I went digging for some answers, and my research led me all the way back to 1783 and the end of the American Revolutionary War.

The war had pretty much bankrupted the Commonwealth of Massachusetts. Seeking relief from its dire financial straits, the Bay State turned to the District of Maine, where it owned vast areas of public lands that were considered to hold great value for settlement and development, and later on, timber. These plans to turn Maine into a cash cow demanded large-scale surveying and boundary marking projects to section off the wilderness for sale.

From 1783 through when Maine acquired its statehood in 1820, and on to 1878, many periodic surveys were done until virtually all publicly owned state lands were subdivided into 6-mile-square township blocks, each identified with one of some 15 land survey designations in a range and number system.

Between 1786 and 1794, William Bingham, a wealthy Philadelphian, purchased two huge land tracts in the District of Maine. The first, a 1,128,000-acre property in the upper Kennebec River valley bisected by the river, became known as Bingham’s Kennebec Purchase and was designated as BKP. Lands east of the Kennebec were further designated EKR; to the west it was WKR. Subsequent surveys west and north of Bingham’s Kennebec lands received the designations of WBKP and NBKP respectively.

In eastern Maine, between the Penobscot River and the St. Croix River, Bingham purchased 1,107,396 acres that had been left over from the Grand Lottery, a failed Massachusetts fundraising and settlement scheme. Bingham’s Penobscot Purchase was designated as BPP and further subdivided into four “divisions,” Southern, Middle, Northern and Eastern, abbreviated as SD, MD, ND and ED.

Between 1825 and 1833, the Monument Line was run from the origin of the state’s eastern line at North Amity in southeastern Aroostook County (the straight line that extends north to Hamlin) westerly in a 90-mile straight line to Seboomook near Moosehead Lake. All townships north of this survey baseline, and a few to its south, carry the designation WELS, for “west of the east line of the state.”

North of the Waldo Patent (NWP) is the designation for 21 townships in portions of Penobscot, Waldo, Piscataquis and Somerset counties surveyed between 1792 and 1842, while the 1792 Titcomb Survey (TS) covered the northeastern corner of what’s now Washington County. Indian Purchase (IP) refers to two townships immediately west of Millinocket and what is present-day Woodville and Mattawamkeag. Old Indian Purchase (OIP) is the 1796 designation for a 30-mile corridor on both sides of the Penobscot River from Orono to Passadumkeag.

Mystery solved, it’s time to grab your Maine Atlas and Gazetteer (note: many unorganized townships have a regular name in addition to a land survey designation) and AMC Maine Mountain Guide, select a few hikes and go exploring. Besides Tunk, here are a several other good ones to check out.

• Sugarloaf Mountain (T5 R7 WELS): Scamper a mile to the open summit for grand views over Katahdin Woods and Waters National Monument.

• Number Five Mountain (T5 R7 BKP WKR): Hike 3 miles to the fire tower for a glorious look at the wildlands of the Moose River region.

• Third Mountain (T7 R9 NWP): Third Mountain Trail and the AT lead 2 miles to Monument Cliff atop the peak and great 100-Mile Wilderness vistas.

• Boundary Bald Mountain, Bald Mountain Township (T4 R3 NBKP): A 2.5-mile hike leads to fabulous views north into Canada from the former fire tower site on top.

Carey Kish of Mt. Desert Island is the author of AMC’s Best Day Hikes Along the Maine Coast and editor of the AMC Maine Mountain Guide. Follow Carey’s adventures on Facebook@CareyKish