Early (pre-1860) printed maps are often to be found in their original context as an integral part of books, or in atlases. For County Durham there is a comprehensive website, Pictures in Print, which includes most of the collections held in the region and some items from the British Library, with digital images. There are bibliographicalreference works on early maps and atlases at Palace Green Library which can help with locating material for other areas.
The most comprehensive holdings of modern maps are of large-scale (6 or 25 inch to the mile - 1:10560 or 1:2500) editions printed in the late 19th and first half of 20th century. Many of them come from estate archives and are marked up withproperty information - notably the Durham Bishopric Halmote Court (property across County Durham) and the Howard (Gilsland, Cumberland) and Grey (Howick, North Northumberland) family estates - and are stored with these collections. Others have comefrom solicitors, university and college departments and miscellaneous donations or purchases. These tend to be stored in the Search Room Map sequence.
The older Ordnance Survey maps (known as the old county series) were produced for County Durham between 1855 and 1950. The Durham maps were organised as follows, and the same principles follow for other counties.County Durham was divided into a grid of 60 rectangles (1-58, 30A, 45A), each of which was covered by one 6 inch to the mile (1:10560) sheet and 16 25 inch to the mile (1:2500) sheets. This grid provides the visual key to finding the map for aparticular place (copies are available in the Search Room, and for Durham online). Thus Durham Sheet 27 is the 6 inch map covering from Durham City across to Shadforth, Durham Sheet 27.1 a 25 inch map covering the top-left sixteenth of that map(Durham City itself). The sheet name is printed top right (only the first edition is called Co. Durham, after that it is Durham), and the date of printing etc. at the bottom centre. The 1st (1856-60) editions were produced in twoversions, either as complete sheets or a set of sheets for each parish leaving blank any area of the sheet not in the parish. A set of field books were printed to accompany this edition. These provide a key to the numbers printed in each field orarea, although the information given is very brief and seldom adds to the information on the map itself.
At the same time as it was producing the 1st edition 6 and 25 inch maps, the Ordnance Survey printed very large scale maps (1:500) of many towns and cities (for a full list see Ordnance survey maps ...). Special Collections holds full or part sets of many of these maps for the region, for example Durham City (1856), Bishop Auckland (1855), Morpeth (1866).