In political geography, an enclave is a piece of land entirely surrounded by the territory of another equivalent-level entity (and only that entity). An exclave is a piece of land that is politically connected to a larger piece but not physically conterminous with it because the territory of other equivalent-level entity or entities entirely surround it. Many entities are both enclaves and exclaves.
In Pennsylvania, every county in the state, other than the counties of Fulton, Philadelphia, Pike and Union, contains at least one municipality surrounded completely by another municipality. While Pennsylvania's urban counties contain few enclaves due to municipal fragmentation, rural areas feature numerous enclaved municipalities. Many resulted from small town centers separating from their rural surrounding areas.
There are at least 338 enclaves (that are not exclaves) in Pennsylvania comprising incorporated places and census-designated places (CDP) within other county subdivisions. Of these, 260 are boroughs (out of 957 in the state), 75 are CDPs (out of 749), two are townships (out of 1547) and one is a city (out of 57). Although each CDP is technically a part of the township(s) in which it is located, these two types of subdivision are considered to be distinct entities.
Usually, the enclave (that is not an exclave) takes the form of a borough that is surrounded by the township of which it was originally a part, but other scenarios are possible, e.g., the borough of Mount Oliver is an enclave of the city of Pittsburgh; Pitcairn borough, of the municipality of Monroeville; Dale borough, of the city of Johnstown; Export borough, of the borough of Murrysville; both New Galilee and Homewood boroughs, of the borough of Big Beaver; the Lackawanna County township of Elmhurst, of Roaring Brook Township; the Tioga County township of Putnam, of Covington Township.
Pennsylvania enclaves that are not exclaves
Adams County Aspers, CDP Bendersville, borough Biglerville, borough Bonneauville, borough Fairfield, borough Hampton, CDP New Oxford, borough Allegheny County Curtisville, CDP Mount Oliver, borough Pennsbury Village, borough Pitcairn, borough West View, borough Armstrong County Dayton, borough Elderton, borough Rural Valley, borough Worthington, borough Beaver County Darlington, borough Homewood, borough Hookstown, borough New Galilee, borough Bedford County Bedford, borough Coaldale, borough Everett, borough Hyndman, borough New Paris, borough Pleasantville, borough Rainsburg, borough Saxton, borough Schellsburg, borough St. Clairsville, borough Woodbury, borough Berks County Amity Gardens, CDP Bally, borough Centerport, borough Flying Hills, CDP Kutztown, borough Laureldale, borough Lenhartsville, borough Mohnton, borough Strausstown, former borough Blair County Bellwood, borough Martinsburg, borough Roaring Spring, borough Tipton, CDP Tyrone, borough Bradford County Canton, borough Le Raysville, borough Monroe, borough Rome, borough Sylvania, borough Troy, borough Bucks County Newtown, borough Richlandtown, borough Silverdale, borough Trumbauersville, borough Woodside, CDP Butler County Bruin, borough East Butler, borough Fairview, borough Harrisville, borough Karns City, borough Mars, borough Nixon, CDP West Sunbury, borough Cambria County Dale, borough Ebensburg, borough Lilly, borough Loretto, borough University of Pittsburgh Johnstown, CDP Wilmore, borough Cameron County Driftwood, borough Emporium, borough Carbon County Beaver Meadows, borough Centre County Bellefonte, borough Centre Hall, borough Coburn, CDP Howard, borough Julian, CDP Madisonburg, CDP Milesburg, borough Pine Glen, CDP Port Matilda, borough Rebersburg, CDP Sandy Ridge, CDP Spring Mills, CDP Stormstown, CDP Unionville, borough Woodward, CDP Chester County Chesterbrook, CDP Honey Brook, borough Kennett Square, borough Toughkenamon, CDP West Grove, borough Clarion County Callensburg, borough Knox, borough Shippenville, borough St. Petersburg, borough Strattanville, borough Clearfield County Coalport, borough Curwensville, borough Grampian, borough Hyde, CDP Irvona, borough Mahaffey, borough Troutville, borough Clinton County Avis, borough Loganton, borough Columbia County Benton, borough Buckhorn, CDP Centralia, borough Jamison City, CDP Jerseytown, CDP Jonestown, CDP Mainville, CDP Mifflinville, CDP Orangeville, borough Slabtown, CDP Stillwater, borough Crawford County Adamsville, CDP Atlantic, CDP Cambridge Springs, borough Canadohta Lake, CDP Geneva, CDP Guys Mills, CDP Harmonsburg, CDP Hydetown, borough Lincolnville, CDP Linesville, borough Spartansburg, borough Springboro, borough Townville, borough Cumberland County Mount Holly Springs, borough New Kingstown, CDP Newburg, borough Plainfield, CDP Dauphin County Berrysburg, borough Dauphin, borough Elizabethville, borough Gratz, borough Halifax, borough Millersburg, borough Skyline View, CDP Williamstown, borough Delaware County East Lansdowne, borough Lima, CDP Elk County Johnsonburg, borough Ridgway, borough Erie County Albion, borough Edinboro, borough McKean, borough Mill Village, borough North East, borough Union City, borough Waterford, borough Fayette County Dunbar, borough Fairchance, borough Markleysburg, borough Ohiopyle, borough Perryopolis, borough Smithfield, borough Vanderbilt, borough Forest County Tionesta, borough Franklin County Greencastle, borough Mont Alto, borough Orrstown, borough Greene County Jefferson, borough Huntingdon County Alexandria, borough Cassville, borough Coalmont, borough Dudley, borough Orbisonia, borough Rockhill Furnace, borough Saltillo, borough Shade Gap, borough Shirleysburg, borough Three Springs, borough Indiana County Armagh, borough Clymer, borough Commodore, CDP Creekside, borough Ernest, borough Marion Center, borough Plumville, borough Shelocta, borough Smicksburg, borough Jefferson County Brockway, borough Reynoldsville, borough Summerville, borough Juniata County McAlisterville, CDP Mexico, CDP Mifflin, borough Mifflintown, borough Thompsontown, borough Lackawanna County Elmhurst Township, township Lancaster County Lititz, borough Maytown, CDP New Holland, borough Strasburg, borough Terre Hill, borough Lawrence County Bessemer, borough S.N.P.J. (Slovenska Narodna Podporna Jednota (Slovene National Benefit Society)), borough Lebanon County Myerstown, borough Schaefferstown, CDP Lehigh County Alburtis, borough Ancient Oaks, CDP Luzerne County Ashley, borough Bear Creek Village, borough Conyngham, borough Freeland, borough Lycoming County Hughesville, borough Muncy, borough Salladasburg, borough McKean County Eldred, borough Kane, borough Mount Jewett, borough Port Allegany, borough Smethport, borough Mercer County Jackson Center, borough Sandy Lake, borough Sheakleyville, borough West Middlesex, borough Mifflin County Belleville, CDP Juniata Terrace, borough Milroy, CDP Newton Hamilton, borough Monroe County Brodheadsville, CDP Mountainhome, CDP Montgomery County Hatfield, borough Narberth, borough North Wales, borough Montour County Washingtonville, borough Northampton County Chapman, borough Pen Argyl, borough Northumberland County McEwensville, borough Mount Carmel, borough Sunbury, city Turbotville, borough Perry County Blain, borough Bloomfield, borough Landisburg, borough Potter County Coudersport, borough Schuylkill County Beurys Lake, CDP Deer Lake, borough Delano, CDP Friedensburg, CDP Girardville, borough Gordon, borough Heckscherville, CDP Hometown, CDP Lavelle, CDP Mahanoy City, borough McKeansburg, CDP Middleport, borough New Philadelphia, borough New Ringgold, borough Oneida, CDP Renningers, CDP Ringtown, borough Sheppton, CDP Snyder County Beavertown, borough Freeburg, borough Middleburg, borough Paxtonville, CDP Troxelville, CDP Somerset County Addison, borough Berlin, borough Boswell, borough Cairnbrook, CDP Central City, borough Davidsville, CDP Edie, CDP Friedens, CDP Indian Lake, borough Jennerstown, borough Meyersdale, borough New Centerville, borough Salisbury, borough Shanksville, borough Somerset, borough Stoystown, borough Ursina, borough Sullivan County Dushore, borough Eagles Mere, borough Laporte, borough Susquehanna County Great Bend, borough Hallstead, borough Montrose, borough New Milford, borough Thompson, borough Tioga County Knoxville, borough Liberty, borough Mansfield, borough Putnam Township, township Roseville, borough Tioga, borough Westfield, borough Venango County Clintonville, borough Cooperstown, borough Seneca, CDP Warren County Clarendon, borough Sheffield, CDP Sugar Grove, borough Youngsville, borough Washington County Burgettstown, borough Claysville, borough West Middletown, borough Wolfdale, CDP Wayne County Bethany, borough Westmoreland County Adamsburg, borough Arona, borough Derry, borough Donegal, borough Export, borough Fellsburg, CDP Harrison City, CDP Herminie, CDP Hostetter, CDP Laurel Mountain, borough Ligonier, borough Millwood, CDP Seward, borough Youngstown, borough Wyoming County Nicholson, borough York County Dillsburg, borough East Prospect, borough Emigsville, CDP Franklintown, borough Glen Rock, borough Hallam, borough Jacobus, borough Loganville, borough New Salem, borough Stewartstown, borough Valley View, CDP Wellsville, borough Windsor, borough Winterstown, borough Yorkana, borough
Pennsylvania exclaves that are not enclaves
To be a true exclave, all potential paths of travel from the exclave to the main region must cross over the territory of a different region or regions having the equivalent governmental administrative level. Two municipalities of Berks County have exclaves. Lower Alsace Township has a southern portion that is disconnected from the main portion of the township by Reading and Mount Penn. Cumru Township has two exclaves, one that is an enclave of Reading and one that is surrounded by Reading and West Reading. Birmingham Township and Chester County have an exclave along a bend in the Brandywine Creek that borders the state of Delaware to the south and is surrounded by Chadds Ford Township and Delaware County on three sides. Three municipalities in Delaware County have exclaves. Springfield Township has an exclave separated from the main body of the township by the village of Swarthmore. Darby Township consists of two non-contiguous areas. Part of Upper Darby is separated from the main body of the township by Aldan and Lansdowne. Three municipalities in Lehigh County have exclaves. Salisbury Township has a smaller western portion that is separated from the larger eastern portion by Allentown and Emmaus. Upper Milford Township has a small exclave that is separated from the rest of the township by Emmaus. Upper Saucon Township has a small exclave that is surrounded by Coopersburg and Springfield Township, Bucks County. In Allegheny County, O'Hara Township consists of five non-contiguous areas, with Sharpsburg, Aspinwall and Fox Chapel separating them. In Lackawanna County, South Abington Township has an isolated section along Glenburn Road surrounded by Clarks Summit borough, Clarks Green borough, and Waverly Township. The township also has several virtual exclaves as it is oddly shaped and surrounds Clarks Summit, Clarks Green, and Waverly Township collectively on three sides. In Lancaster County, East Lampeter Township, Lancaster Township, and Manheim Township all have several small exclaves within Lancaster City. In Somerset County, Middlecreek Township has an exclave surrounded by Seven Springs and Jefferson Township.
Pennsylvania pene-enclaves/exclaves Like enclaves and exclaves, pene-enclaves and pene-exclaves are regions that are not contiguous with the main land region and have land access only through another region or regions having the equivalent governmental administrative level. Unlike enclaves and exclaves, they are not entirely surrounded by outside territory. Hence, they are enclaves or exclaves for practical purposes, without meeting the strict definition.