There has been a census every ten years since 1801, excluding 1941, but only those returns from 1841 onwards carry details of named residents. The latest that is currently available for inspection is for 1911. All census returns are held at the National Records of Scotland in Edinburgh and can be accessed online at the ScotlandsPeople website.
The 1841 and 1851 censuses were organised on a parish basis. The census reference number will be the same as the Old Parish Register (OPR) reference number. From 1861, censuses were organised on a registration district basis. There were some differences between the 2 different administrative areas. Some addresses will therefore appear in a different area, under a different reference number, from one census to another. Differences are noted on the relevant parish pages. There is a list of the census parish / district reference numbers here.
The 1841, 1851, 1861, 1871, 1881, 1891, 1901 and 1911 censuses are indexed and online at the ScotlandsPeople website. They can be searched and copies of the census pages can be purchased. For 1881 only, transcripts can also be purchased.
The 1841, 1851, 1861, 1871, 1881, 1891 and 1901 censuses are available on ancestry.co.uk (indexed transcripts, no images of the pages).
The 1841, 1851, 1861, 1871, 1881, 1891 and 1901 censuses are available on findmypast.co.uk (indexed transcripts, no images of the pages).
The returns for 1841, 1851, 1861 and 1871 are available on the FreeCEN website.
The census returns for 1841, 1851, 1861, 1871, 1881 and 1891 have been microfilmed by the LDS church and may be consulted in their Family History Centres around the world. The LDS library catalogue numbers for the films are given here.
Microfilms of the 1841, 1851, 1861, 1871, 1881, 1891 and 1901 census are held by the Dumfries and Galloway Family History Society and are in some local libraries.
The 1881 census has been transcribed and indexed and is available at LDS Family History Centres, some libraries and some family history societies.
1841 census surname indexes for every parish in the county are available from the Dumfries and Galloway Family History Society.
Transcripts of the 1851 census for some parishes are on the Maxwell Ancestry site. An index to the 1851 census is available online, created by the Friends of the Archives of Dumfries and Galloway.
An index to the 1891 census is available on microfiche at some local libraries and family history societies.
A Vision of Britain provides census statistics and graphs from the 1801 census onwards.
Histpop, the online historical population reports website, in its census section provides access to all the published population reports for Britain and Ireland from 1801 - 1937. The site has a huge amount of statistical information both at a county level and at a parish or district level. There is no personal information on the site.