Numerous communities are too small to be on oridinary maps, have changed names over time, or have disappeared completely. Here is a list of place names, past and present, along with a few outside the county that may surprise someone not familiar with the region. The term “community” is used very loosely here. These places have been mentioned in a book or marked on a map, but may never have been a gathering of people.
| Apsley | village in Anstruther Twp. Post office from 1865. | |
| Allendale Mills | early name for Lang in Otonabee Twp | |
| Alpine Village | community in Harvey Twp | |
| Amhurst | former name for Cobourg | |
| Anstruther Lake | community in Anstruther Twp | |
| Ashburnham | former village now part of Peterborough. That part of Peterborough on the east side of the Otonabee River. | |
| Ashby Mill | community in Belmont Twp | |
| Asphodel | former name for Westwood in Asphodel Twp. The post office used the name from 1836 to 1861. | |
| Asphodel | railway stop in Asphodel Twp | |
| Asphodel Bridge | early name for Hastings (community) | |
| Asphodel Mills | location unknown | |
| Assumption | community in Otonabee Twp | |
| Auburn Mills | community in Smith Twp, now part of the city of Peterborough | |
| Bensfort Bridge | community in Otonabee Twp | |
| Big Cedar | community in Burleigh Twp. | |
| Birdsalls | community in Asphodel Twp | |
| Birdsalls Station | community in Asphodel Twp | |
| Blairton | community in Belmont Twp | |
| Blairton Station | community in Belmont Twp | |
| Blezard | community in Otonabee Twp | |
| Bloomfield | former name for Bailieboro. | |
| Blue Mountain | community in Methuen Twp | |
| Bridgenorth | village in Smith Twp on Chemong Lake. ; Start of a significant portage (to Peterborough) and a former rail-head. | |
| Broads Corners | former community on Stony Lake Road at Dummer-Douro boundary | |
| Browns Falls | Burleigh Twp, on Eels Creek. | |
| Buckhorn | community and post office in Harvey and Smith Twps. Although the community has always been Buckhorn, the post office was known as Halls Bridge from its establishment in 1860 to 1947. | |
| Burleigh Falls | community in Harvey Twp. Post office from 1864. | |
| Burleigh Road Settlement | early name for Apsley | |
| Byersville | former community in North Monaghan, now part of the city of Peterborough | |
| Cameron | community of border of Otonabee and Asphodel Twps | |
| Campbelltown | community in Otonabee Twp. | |
| Canada West | former name for Ontario (18** - 1867) when it was part of the colony of Canada. (The other part was Canada East, now Quebec) | |
| Catchacoma | community in Cavendish Twp | |
| Cavan | community and post office in Cavan Twp. The post office has been known as that since opening on 1830 Jan 6 but the community was for some time known as Cavanville. | |
| Centerville | former (to 1853) name for South Monaghan. | |
| Centre Dummer | community in Dummer Twp | |
| Chase Corners | community in Belmont Twp | |
| Chemong | lake between Smith and Ennismore Twps. Originally spelled Shemong (as it should be pronounced) from the Indian word for canoe. | |
| Chemong | former name for the Indian reservation of Curve Lake. | |
| Chemong | name of a community on Chemong Lake at the head of the Peterborough and Chemong Railway (this was about three miles north of Bridgenorth). The community did not survive the collapse of the railway. | |
| Chemong Heights | community in Smith Twp on Chemong Lake | |
| Chemong Park | community in Smith Twp on Chemong Lake | |
| Clarauay? | community in Otonabee Twp | |
| Clarina | community in Dummer Twp | |
| Clanricade | community in Anstruther Twp | |
| Clydesdale | community in Chandos Twp. Named in 1878 because the postmaster came from Clydebank | |
| Cobourg | town in Northumberland Co on the shore of Lake Ontario. Port of entry for many early settlers. | |
| Colborne | district, administrative unit for the area from 1838 Apr 20 to 1849 May 30. | |
| Colquhouns Corners | pre 1886 name for Cottesloe, Dummer Twp | |
| Connaught Shore | community in Ennismore Twp | |
| Cordova Mines | community in Belmont Twp (may be called Cordova). An early name was Warriston | |
| Cottesloe | community in Dummer Twp, so named from 1886. | |
| Crawford’s Grove | community in North Monaghan | |
| Crook’s Rapids | early name for Hastings (community) | |
| Crowes Landing | community in Dummer Twp, on Stony Lake. | |
| Crystal Springs | community in Otonabee Twp | |
| Curve Lake | community and Indian Reservation in Smith Twp | |
| Deer Bay | community in Smith Twp | |
| Donwood | community on border between Douro and Otonabee Twps. | |
| Douro | Township and community within that township. | |
| Downers Corners | now part of Peterborough. Corner of Ashburnham and Lansdown. | |
| Drummond | railway stop in Otonabee Twp | |
| Dummer Mills | early name for Warsaw | |
| Ennismore | Township and community within that township. | |
| Ewan | community in Galway Twp | |
| Fairview | ||
| Fifes Bay | community in Smith Twp, on Chemong Lake. | |
| Five Corners | community in Douro Twp | |
| Floods Landing | community in Ennismore Twp | |
| Flynns Turn | community in Harvey Twp | |
| Fortesque | community on border between Cavendish and Glamorgan Twps | |
| Fowlers Corners | community on border of Smith Twp and Emily Twp. | |
| Fraserville | community on border of North Monaghan Twp and Cavan Twp. | |
| Freeman Corners | community in Belmont Twp | |
| Galesburg | community in Douro Twp | |
| Gannon Beach | community in Ennismore Twp | |
| Gannon Village | community in Ennismore Twp (may be called Gannons Narrows) | |
| Gilchrist Bay | community in Dummer Twp, on Stony Lake | |
| Gilchrist’s Mills | early name for Keene | |
| Glen Alda | community in Chandos Twp | |
| Graham's | former name for Bailieboro. | |
| Graystock | community in Otonabee Twp | |
| Guerin | community on border of Otonabee and Douro Twps | |
| Halls Bridge | name of the post office at Buckhorn from 1860 to 1947. | |
| Halls Glen | community in Dummer Twp | |
| Hastings | community in Asphodel Twp and Percy Twp (Northumberland Co) | |
| Haultain | former community in Burleigh Twp. Post office from 1866. | |
| Havelock | village in Belmont Twp. Note that there is an Old Havelock (pre 1881) and a New Havelock, built when the railway went through. | |
| Hawleys Settlement | former name for Owenbrook, Chandos Twp | |
| Herriots Falls | Second name for Lakefield (also spelled Heriots or Harriots) used to 1851 | |
| Hiawatha | community and Indian reservation in Otonabee Twp | |
| Hill Settlement | community in Dummer Twp | |
| Hope | community in Otonabee Twp | |
| Indian River | community in Otonabee Twp | |
| Iron Mine | early name for Blairton (the name changed in the late 1860's) | |
| Jack Lake | community in Methuen Twp | |
| Jermyn | community in Otonabee Twp | |
| Kasshabog Lake | community in Methuen Twp | |
| Kawartha Hideaway | community in Harvey Twp | |
| Kawartha Park | community in Smith Twp | |
| Keelers Mill | original name for Norwood. | |
| Keene | village in Otonabee Twp, founded in 1825 by Dr John Gilchrist. Early name Gilchrist’s Mills. The post office was called Otanabee from 1836 to 1858. | |
| Kendry | railway stop on border between North Monaghan and Cavan Twps. | |
| Katchewanooka | lake between Smith and Douro Twps. The Indian name was Ketchewanoonka (place at the head of the rapids) | |
| Keelers Mills | former name for Norwood | |
| Kimberley Park | community in Ennismore Twp | |
| Kinmount | community in Victoria Co, almost on the boundary with Galway Twp. | |
| Lakefield | village in Smith and Douro Twps. Former rail-head and terminus for steamers to the "upper lakes". The post office was called North Douro. | |
| Lakehurst | community in Harvey Twp | |
| Lang | community in Otonabee Township, established about 1823-25. Early name Allendale Mills | |
| Lasswade | community in Chandos Twp | |
| Little Lake | small lake in the Otonabee river in Peterborough. The Indian name was Nogojiwanong (lake at the end of the rapids) | |
| MacDonald Bay | community in Methuen Twp | |
| Martinville | community in North Monaghan | |
| Mathers Corners | community in Otonabee Twp. | |
| Mathison | early name for Havelock. | |
| McCrackens Landing | community and post office in Dummer Twp, on Stony Lake. | |
| Mississagua Landing | community in Cavendish Twp | |
| Monaghan | the name of the post office in Bailieboro from 1830 Jan 6 to 1831 Dec and at a site a bit to the north of Bailieboro (Robert Waddell's home) for about six months in 1836. | |
| Mount Irwin | community in Galway Twp | |
| Mount Julian | community in Burleigh Twp | |
| Mud Lake | original name for Chemong Lake. The Indians called it Wabuscommoug (lake of earth) | |
| Murray Hill | community on border of North Monaghan Twp and Cavan Twp. | |
| Nassau Mills | community in Douro Twp (now site of Trent University) | |
| Nelson | former name for Lakefield | |
| Nelsons Falls | first name for Lakefield | |
| Nephton | community in Methuen Twp | |
| Newcastle | district, administrative unit for the area from 1802 Jun 23 to 1838 Apr 20. | |
| Nogies Creek | community in Harvey Twp | |
| North Douro | name of the post office at Lakefield from 1856 to 1875. | |
| Northumberland | county to the south of Peterborough County. Settled long before Peterborough, most early settlers came through Northumberland on their way to Peterborough. | |
| Norwood | village in Asphodel Twp | |
| Oak Lake | community in Methuen Twp | |
| Oak Orchard | community in Harvey Twp | |
| Ontario | name of the province since 1867 and the name of a county between Peterborough and Toronto. | |
| Otanabee | name of post office in home of Charles Rubidge Sr in Otanabee Twp from 1832 to 1836, when it was moved to Keene. It and its more recent spelling Otonabee was used as the name of the post office in Keene until 1858. | |
| Otonabee | name of township and river. Spelled Otanabee until 1845. It means "dangerous waters" and the original spelling (with the O pronounced as in Ottawa) would be the correct Indian pronunciation. | |
| Owenbrook | community in Chandos Twp, named in 1906 after the postmaster (Owen) and an early settler (Brooks) | |
| Peterborough | city and county seat. The city so named since 1825 Dec (formerly Scotts Plains). First spelled Peterborro. The post office was Peterboro from opening on 1830 Jan 5 to 1933, except for three years in the 1890's. The county was formed 1841 Oct 14 but assumed power from the District on 1849 May 30. | |
| Peterborough East | former name for the village of Ashburnham (now part of the city of Peterborough). A previous name was Scotch Village. | |
| Point Pleasant | community in Harvey Twp | |
| Port Hope | town in Durham Co on the shore of Lake Ontario. Port of entry for many early settlers. | |
| Preneveau | community in Belmont Twp | |
| Purdyville | colloquial name for Glen Alda, Chandos Twp, named after Sam Purdy, a significant landowner. | |
| Roach Point | community in Otonabee Twp | |
| Rockcroft | community in Harvey Twp | |
| Rockdale | community in Belmont Twp | |
| Rose Island | community in Chandos Twp | |
| Round Lake | community in Belmont Twp | |
| Rush Point | community in Belmont Twp | |
| Scotch Village | former name for Ashburnham (now part of the city of Peterborough) | |
| Scotch Settlement | former name for Ashburnham (now part of the city of Peterborough) | |
| Scott Settlement | community in Chandos Twp | |
| Scotts Landing | community in Chandos Twp | |
| Scotts Mills | former community in Harvey Twp | |
| Scotts Plains | former name for Peterborough before 1825. | |
| Selby | third name for Lakefield (1851) | |
| Selwyn | community in Smith Twp. | |
| Silver Lake | community on border between Galway and Somerville Twps | |
| Smiths Creek | former name for Port Hope. | |
| South Beach | community in Douro Twp | |
| South Douro | community and post office in Douro Twp | |
| South Dummer | community on border of Asphodel and Dummer Twps | |
| South Monaghan | community and post office in South Monaghan Twp, so named since 1853 (formerly Centreville) | |
| Springville | community of border of North Monaghan Twp and Cavan Twp | |
| Squaknegosippi | Indian name for Indian River. | |
| Stewart Hall | community in Otonabee Twp. | |
| Stewart Heights | community in Smith Twp, on Chemong Lake | |
| Stockdale | community in Harvey Twp | |
| Stony Ridge | community in Burleigh Twp | |
| Tanner Settlement | area around Chandos post office, in Chandos Twp | |
| Terra View Heights | community in Smith Twp | |
| Thompsons Falls | former name for Lakefield. | |
| Thompsons Rapids | former name for Lakefield. | |
| Toronto | capital of Ontario and long an administrative site for the region. Located on Lake Ontario at the end of a major Indian route north. Former name York. There is also a Toronto Twp in Ontario. | |
| Toronto | former name for Port Hope. | |
| Trent River | community on border of Belmont Twp and Northumberland Co. | |
| Union Creek | community on border of Galway Twp and Victoria Co. | |
| Upper Canada | former name for Ontario when it was a separate colony (17** - 18**). (Lower Canada was another colony, now Quebec). | |
| Vansickle | community on border of Methuen Twp and Hastings Co | |
| Victoria | county to the west of Peterborough. For a time the two counties were administratively one. | |
| Victoria Springs | community in Smith Twp | |
| Village Meadows | community in Smith Twp | |
| Villiers | community in Otonabee Twp | |
| Wallace Point | community in Otonabee Twp | |
| Warriston | early name for Cordova | |
| Warsaw | village in Dummer Twp. Named, by Thomas Choate, after Warsaw NY, where he had lived. | |
| Westwood | community and post office in Asphodel Twp, so named since 1861 (previously Asphodel) although the term was in use before that. | |
| Williamsburg | community in Otonabee Twp C17 L 12 (on the river) | |
| Windward Shore | community in Ennismore Twp | |
| Woodland Acres | community in Smith Twp. | |
| Woodview | community and post office in Burleigh Twp. | |
| Woodview | community in Otonabee Twp | |
| York | former name for Toronto City and the name of the county Toronto is in. | |
| Youngs Cove | community in Ennismore Twp | |
| Youngs Point | community in Smith Twp | |
| Youngstown | community in Ennismore Twp. | |
| Zion | community in Otonabee Twp. |