Although the modern county of Greater Manchester was not created until 1974, the history of its constituent settlements goes back centuries. There is evidence of Iron Age habitation, particularly at Mellor, and Celtic activity in a settlement named Chochion, believed to have been an area of Wigan settled by the Brigantes. Stretford was also part of the land believed to have been occupied by the Celtic Brigantes tribe, and lay on their border with the Cornovii on the southern side of the River Mersey. The remains of 1st-century forts at Castlefield in Manchester, and Castleshaw Roman fort in Saddleworth, are evidence of Roman occupation. Much of the region was omitted from the Domesday Book of 1086; Redhead states that this was because only a partial survey was taken, rather than sparsity of population.
During the Middle Ages, much of what became Greater Manchester lay within the hundred of Salfordshire – an ancient division of the county of Lancashire. Salfordshire encompassed several parishes and townships, some of which, like Rochdale, were important market towns and centres of England's woollen trade. The development of what became Greater Manchester is attributed to a shared tradition of domestic flannel and fustian cloth production, which encouraged a system of cross-regional trade. In the late-18th century, the Industrial Revolution transformed the local domestic system; mechanisation enabled the industrialisation of the region's textile trade, triggering rapid growth in the cotton industry and expansion in ancillary trades. Infrastructure such as rows of terraced housing, factories and roads were constructed to house labour, transport goods, and produce cotton goods on an industrial scale for a global market. The townships in and around Manchester began expanding "at an astonishing rate" around the turn of the 19th century as part of a process of unplanned urbanisation brought on by a boom in industrial textile production and processing. This population increase resulted in the "vigorous concentric growth" of a conurbation between Manchester and an arc of surrounding mill towns, formed from a steady accretion of houses, factories and transport infrastructure. Places such as Bury, Oldham and Bolton played a central economic role nationally, and by the end of the 19th century had become some of the most important and productive cotton-producing towns in the world. However, it was Manchester that was the most populous settlement, a major city, the world's largest marketplace for cotton goods, and the natural centre of its region. By 1835 "Manchester was without challenge the first and greatest industrial city in the world"; and by 1848 urban sprawl had fused the city to its surrounding towns and hinterland to form a single continuous conurbation. In the 1910s, local government reforms to administer this conurbation as a single entity were proposed.
In the 18th century, German traders had coined the name Manchesterthum to cover the region in and around Manchester. However, the English term "Greater Manchester" did not appear until the 20th century. One of its first known recorded uses was in a 1914 report put forward in response to what was considered to have been the successful creation of the County of London in 1889. The report suggested that a county should be set up to recognise the "Manchester known in commerce", and referred to the areas that formed "a substantial part of South Lancashire and part of Cheshire, comprising all municipal boroughs and minor authorities within a radius of eight or nine miles of Manchester". In his 1915 book Cities In Evolution, urban planner Sir Patrick Geddes wrote "far more than Lancashire realises, is growing up another Greater London".
Most of Greater Manchester lay within the ancient county boundaries of Lancashire; those areas south of the Mersey and Tame were in Cheshire. The Saddleworth area and a small part of Mossley are historically part of Yorkshire and in the south-east a small part in Derbyshire. The areas that were incorporated into Greater Manchester in 1974 previously formed parts of the administrative counties of Cheshire, Lancashire, the West Riding of Yorkshire and of eight independent county boroughs. By the early 1970s, this system of demarcation was described as "archaic" and "grossly inadequate to keep pace both with the impact of motor travel, and with the huge increases in local government responsibilities".
The Manchester Evening Chronicle brought to the fore the issue of "regional unity" for the area in April 1935 under the headline "Greater Manchester – The Ratepayers' Salvation". It reported on the "increasing demands for the exploration of the possibilities of a greater merger of public services throughout Manchester and the surrounding municipalities". The issue was frequently discussed by civic leaders in the area at that time, particularly those from Manchester and Salford. The Mayor of Salford pledged his support to the idea, stating that he looked forward to the day when "there would be a merging of the essential services of Manchester, Salford, and the surrounding districts constituting Greater Manchester." Proposals were halted by the Second World War, though in the decade after it, the pace of proposals for local government reform for the area quickened. In 1947, Lancashire County Council proposed a three "ridings" system to meet the changing needs of the county of Lancashire, including those for Manchester and surrounding districts. Other proposals included the creation of a Manchester County Council, a directly elected regional body. In 1951, the census in the UK began reporting on South East Lancashire as a homogeneous conurbation.
The Local Government Act 1958 designated the south east Lancashire area (which, despite its name, included part of north east Cheshire), a Special Review Area. The Local Government Commission for England presented draft recommendations, in December 1965, proposing a new county based on the conurbation surrounding and including Manchester, with nine most-purpose boroughs corresponding to the modern Greater Manchester boroughs (excluding Wigan). The review was abolished in favour of the Royal Commission on Local Government before issuing a final report.
The Royal Commission's 1969 report, known as the Redcliffe-Maud Report, proposed the removal of much of the then existing system of local government. The commission described the system of administering urban and rural districts separately as outdated, noting that urban areas provided employment and services for rural dwellers, and open countryside was used by town dwellers for recreation. The commission considered interdependence of areas at many levels, including travel-to-work, provision of services, and which local newspapers were read, before proposing a new administrative metropolitan area. The area had roughly the same northern boundary as today's Greater Manchester (though included Rossendale), but covered much more territory from Cheshire (including Macclesfield, Warrington, Alderley Edge, Northwich, Middlewich, Wilmslow and Lymm), and Derbyshire (the towns of New Mills, Whaley Bridge, Glossop and Chapel-en-le-Frith – a minority report suggested that Buxton be included). The metropolitan area was to be divided into nine metropolitan districts, based on Wigan, Bolton, Bury/Rochdale, Warrington, Manchester (including Salford and Old Trafford), Oldham, Altrincham, Stockport and Tameside. The report noted "The choice even of a label of convenience for this metropolitan area is difficult". Seven years earlier, a survey prepared for the British Association intended to define the "South-East Lancashire conurbation" noted that "Greater Manchester it is not ... One of its main characteristics is the marked individuality of its towns, ... all of which have an industrial and commercial history of more than local significance". The term Selnec (or SELNEC) was already in use as an abbreviation for south east Lancashire and north east Cheshire; Redcliffe-Maud took this as "the most convenient term available", having modified it to south east Lancashire, north east and central Cheshire.
Following the Transport Act 1968, in 1969 the SELNEC Passenger Transport Executive (an authority to co-ordinate and operate public transport in the region) was set up, covering an area smaller than the proposed Selnec, and different again to the eventual Greater Manchester. Compared with the Redcliffe-Maud area, it excluded Macclesfield, Warrington, and Knutsford but included Glossop and Saddleworth in the West Riding of Yorkshire. It excluded Wigan, which was in both the Redcliffe-Maud area and in the eventual Greater Manchester (but had not been part of the 1958 act's review area).
Redcliffe-Maud's recommendations were accepted by the Labour-controlled government in February 1970. Although the Redcliffe-Maud Report was rejected by the Conservative government after the 1970 general election, there was a commitment to local government reform, and the need for a metropolitan county centred on the conurbation surrounding Manchester was accepted. The new government's original proposal was much smaller than the Redcliffe-Maud Report's Selnec, with areas such as Winsford, Northwich, Knutsford, Macclesfield and Glossop retained by their original counties to ensure their county councils had enough revenue to remain competitive (Cheshire County Council would have ceased to exist). Other late changes included the separation of the proposed Bury/Rochdale authority (retained from the Redcliffe-Maud report) into the Metropolitan Borough of Bury and the Metropolitan Borough of Rochdale. Bury and Rochdale were originally planned to form a single district (dubbed "Botchdale" by local MP Michael Fidler) but were divided into separate boroughs. To re-balance the districts, the borough of Rochdale took Middleton from Oldham. During the passage of the bill, the towns of Whitworth, Wilmslow and Poynton successfully objected to their incorporation in the new county.
The Local Government Act 1972 reformed local government in England by creating a system of two-tier metropolitan and non-metropolitan counties and districts throughout the country. The act formally established Greater Manchester on 1 April 1974, although Greater Manchester County Council (GMCC) had been running since elections in 1973. The leading article in The Times on the day the Local Government Act came into effect noted that the "new arrangement is a compromise which seeks to reconcile familiar geography which commands a certain amount of affection and loyalty, with the scale of operations on which modern planning methods can work effectively". Frangopulo noted that the creation of Greater Manchester "was the official unifying of a region which, through history and tradition, had forged for itself over many centuries bonds ... between the communities of town and village, each of which was the embodiment of the character of this region". The name Greater Manchester was adopted, having been favoured over Selnec by the local population.
By January 1974, a joint working party representing Greater Manchester had drawn up its county Structure Plan, ready for implementation by the Greater Manchester County Council. The plan set out objectives for the forthcoming metropolitan county. The highest priority was to increase the quality of life for its inhabitants by improving the county's physical environment and cultural facilities which had suffered following deindustrialisation—much of Greater Manchester's basic infrastructure dated from its 19th-century growth, and was unsuited to modern lifestyles. Other objectives were to reverse the trend of depopulation in central-Greater Manchester, to invest in country parks to improve the region's poor reputation on leisure facilities, and to improve the county's transport infrastructure and patterns.
Because of political objection, particularly from Cheshire, Greater Manchester covered only the inner, urban 62 of the 90 former districts that the Royal Commission had outlined as an effective administrative metropolitan area. In this capacity, GMCC found itself "planning for an arbitrary metropolitan area ... abruptly truncated to the south", and so had to negotiate several land-use, transport and housing projects with its neighbouring county councils. However a "major programme of environmental action" by GMCC broadly succeeded in reversing social deprevation in its inner city slums. Leisure and recreational successes included the Greater Manchester Exhibition Centre (better known as the G-Mex centre and now branded Manchester Central), a converted former railway station in Manchester city centre used for cultural events, and GMCC's creation of five new country parks within its boundaries. GMCC was, however, criticised for being too Manchester-centric by representatives from the outer suburbs.
Unlike the other counties created by the Act, Greater Manchester was never adopted as a postal county by the Royal Mail. A review in 1973 noted that "Greater Manchester" would be unlikely to be adopted because of confusion with the Manchester post town. The component areas of Greater Manchester therefore retained their pre-1974 postal counties until 1996, when the counties were abolished.
A decade after they were established, the mostly Labour-controlled metropolitan county councils and the Greater London Council (GLC) had several high-profile clashes with the Conservative government of Margaret Thatcher, with regards overspending and high rates charging. Government policy on the issue was considered throughout 1982, and the Conservative Party put a "promise to scrap the metropolitan county councils" and the GLC, in their manifesto for the 1983 general election. Greater Manchester County Council was abolished on 31 March 1986 under the Local Government Act 1985. That the metropolitan county councils were controlled by the Labour Party led to accusations that their abolition was motivated by party politics: the general secretary of the National Association of Local Government Officers described it as a "completely cynical manoeuvre". Most of the functions of GMCC were devolved to the ten Greater Manchester metropolitan district councils, though functions such as emergency services and public transport were taken over by joint boards and continued to be run on a county-wide basis. The Association of Greater Manchester Authorities (AGMA) was established to continue much of the county-wide services of the county council. The metropolitan county continues to exist in law, and as a geographic frame of reference, for example as a NUTS 2 administrative division for statistical purposes within the European Union. Although having been a Lieutenancy area since 1974, Greater Manchester was included as a ceremonial county by the Lieutenancies Act 1997 on 1 July 1997.
In 1998, the people of Greater London voted in a referendum in favour of establishing a new Greater London Authority, with mayor and an elected chamber for the county. The New Local Government Network proposed the creation of a new Manchester City Region based on Greater Manchester and other metropolitan counties as part of on-going reform efforts, while a report released by the Institute for Public Policy Research's Centre for Cities proposed the creation of two administrative city regions based on Manchester and Birmingham. In July 2007, The Treasury published its Review of sub-national economic development and regeneration, which stated that the government would allow those city regions that wished to work together to form a statutory framework for city regional activity, including powers over transport, skills, planning and economic development. In January 2008, AGMA suggested that a formal government structure be created to cover Greater Manchester. The issue resurfaced in June 2008 with regards to proposed congestion charging in Greater Manchester; Sir Richard Leese (leader of Manchester City Council) said "I've come to the conclusion that [a referendum on congestion charging should be held] because we don't have an indirectly or directly elected body for Greater Manchester that has the power to make this decision". On 14 July 2008 the ten local authorities in Greater Manchester agreed to a strategic and integrated cross-county Multi-Area Agreement; a voluntary initiative aimed at making district councils "work together to challenge the artificial limits of boundaries" in return for greater autonomy from the central government of the UK. A referendum on the Greater Manchester Transport Innovation Fund was held in December 2008, in which voters "overwhelmingly rejected" plans for public transport improvements linked to a peak-time weekday-only congestion charge.
Following a bid from AGMA highlighting the potential benefits in combatting the late-2000s financial crisis, it was announced in the 2009 United Kingdom Budget that Greater Manchester and the Leeds City Region would be awarded Statutory City Region Pilot status, allowing (if they desired) for their constituent district councils to pool resources and become statutory Combined Authorities with powers comparable to the Greater London Authority. The stated aim of the pilot was to evaluate the contributions to economic growth and sustainable development by Combined Authorities. The Local Democracy, Economic Development and Construction Act 2009 enabled the creation of a Combined Authority for Greater Manchester with devolved powers on public transport, skills, housing, regeneration, waste management, carbon neutrality and planning permission, pending approval from the ten councils. Such strategic matters would be decided on via an enhanced majority rule voting system involving ten members appointed from among the councillors of the metropolitan boroughs (one representing each borough with each council nominating one substitute) without the input of central government. The ten district councils of Greater Manchester approved the creation of the Greater Manchester Combined Authority (GMCA) on 29 March 2010, and submitted final recommendations for a constitution to the Department for Communities and Local Government and the Department for Transport. On 31 March 2010 the Communities Secretary John Denham approved the constitution and launched a 15-week public consultation on the draft bill together with the approved constitution. Following requests by the Association of Greater Manchester Authorities, which was superseded by the GMCA, the new authority came into being on 1 April 2011. On the same day, the Transport for Greater Manchester Committee was also formed from a pool of 33 councillors allocated by council population (roughly one councillor per 75,000 residents) to scrutinise the running of Greater Manchester's transport bodies and their finances, approve the decisions and policies of said bodies and form strategic policy recommendations or projects for the approval of the Combined Authority.
On 3 November 2014, George Osborne, the Chancellor of the Exchequer, announced that there would be an eleventh member of the GMCA — a directly elected Mayor of Greater Manchester, with "powers over transport, housing, planning and policing" from 2017.