The extent to which under-performing secondary schools are concentrated in particular parts of the country is deeply troubling, the head of Ofsted has warned, and is leading to "nothing short of a divided nation".
Sir Michael Wilshaw said a lack of political will is contributing to the "growing divide" which means that of the 173 failing secondary schools in the country, 130 are in the North and Midlands, with just 43 in the South.
His fourth annual Ofsted report found there are 16 local authority areas in England where fewer than 60% of children attend good or outstanding secondary schools, have lower than national GCSE attainment and make less than national levels of expected progress.
All but three of these are in the North and Midlands.
These areas are Middlesbrough, Hartlepool, Blackpool, Oldham, Doncaster, Bradford, Barnsley, Stoke-on-Trent, Derbyshire, Liverpool, Knowsley, St Helens and Salford.
"The extent to which under-performing secondary schools are concentrated in particular parts of the country is deeply troubling," the chief inspector of schools said.
"We are witnessing an educational division of the country after age 11, with secondary schools performing well overall in the South but struggling to improve in the North and Midlands.
"The facts are stark. Compared to secondary school children in the South, those in the North and Midlands on average make less progress in English and maths, perform worse at GCSE and attain fewer top grades at A-level.
"If left unaddressed, the consequences will be profound. Our society, our future prosperity and development rely on the better education of our children.
"As things stand, too many secondary schools in the North and Midlands are failing to equip young people with the skills and knowledge they and the country need.
"I fear that unless we resolve these divisions our country's educational progress will be seriously impeded and we will not be able to compete as well with our international competitors."
Sir Michael said more good leaders and teachers, and a greater focus on the most disadvantaged, was needed to turn things around.
His report argues the divide cannot simply be explained away by the higher levels of economic deprivation in the North and Midlands.
It points out there is no difference in the quality of primary schools across the country or in the achievement of seven-year-olds and 11-year-olds at Key Stage 1 and Key Stage 2.
He said the lower standards in secondary schools in the North and Midlands have a direct impact on outcomes for children and young people.
Compared with children and young people in the rest of the country, those living in the North and Midlands make five percentage points less progress from Key Stage 2 to 4 in English and six points less progress in maths. They are also four percentage points behind in achieving five GCSEs grades A* to C, including English and maths.
The report said Bradford "stands out" as a city where standards have been far too low, for many years, across both primary and secondary schools.
There are almost 40,000 pupils there who attend schools that are less than good and, as a result, pupils in Bradford under-perform compared with national levels on almost every major measure of progress and attainment at ages five, seven, 11 and 16.
He said there is now an urgent need for the same type of collective action by local politicians, MPs, chief executives and headteachers that was seen in London in the late 1990s to raise secondary school standards in towns across the North and Midlands.
If cities like Manchester, Leeds and Sheffield are to be the engine rooms of a Northern Powerhouse, they need to work with the towns on their borders to raise attainment and close skills gaps across a wider area, he said.
Action is needed at a national level to tackle the issue, including financial incentives to get trainees to start their career in the areas and schools that need them most, and thought given to a form of "golden handcuffs" to encourage teachers to keep on working in the state system that trained them.