The new unitary councils will be responsible for all council services
Millions of people in seven English counties now come under new council areas, as a result of the biggest local government shake-up in 30 years.
Replacing 44 districts and counties with nine "supersized" authorities will save £100m, according to ministers.
All local services in Cheshire, Bedfordshire, Cornwall, Northumberland, Durham, Shropshire and Wiltshire will be run by unitary authorities.
Opponents say the government ignored local people who did not want change.
Many of the district councils were opposed to the changes. Two of them, Congleton in Cheshire, and Shrewsbury and Atcham in Shropshire, failed in a legal challenge to them.
It meant each of the counties would be run by a single council, except Cheshire and Bedfordshire where two new unitaries have been created.
The government says 300 senior posts will be slashed to save £22m per year for frontline services.
It says the changes will result in simpler access to services for people, stronger lobbying powers for larger councils and better value for money through economies of scale.
Local government minister John Healey said: "This is not a cosmetic make-over or just a new logo on a council tax bill. Nor is it just a cost-cutting exercise.
"It's about the nine areas making the clear case that they can serve their residents better by top-to-bottom reform, and stripping out a layer of local government."
Mr Healey, who welcomed the new councils with a video message on the YouTube website, said the challenge was now for new councils to deliver on promises of better services at less cost.
All councils in Scotland and Wales are run on a unitary basis, while most services in Northern Ireland are run by separate bodies.
Northern Ireland also has unitary councils - though some functions, which in other parts of the UK would be undertaken by councils, are provided by government departments or agencies. These functions include planning, roads, water and conservation.
About 3.2 million residents will be represented by the new English authorities, which replace the two-tier system of counties and districts in the affected areas.
Some, like those in the two new unitary authority areas of Cheshire East, and Chester and Cheshire West, elected councillors to the incoming bodies last year.
Others will vote in June.
WHAT DO THE COUNCILS DO?
provide education, social services, public transport and libraries, and are split into districts
- also known as
- look after council housing, leisure facilities, planning decisions and bin collections
, which now cover 60% of England and go under a variety of names, run all local services
- also known as
councils - look after some allotments, public toilets, street lights, parks and ponds, war memorials, local halls and community centres.
Across the seven areas, the total number of councillors will be reduced from 2037 to 725. This does not include parish and town councillors, who have lesser powers.
Cllr Lionel Grundy, former leader of Kennet District Council in Wiltshire, which closed down on Tuesday, said an independent poll showed people in the borough did not want a larger council.
"We ran an efficient little council and the public seemed to be quite satisfied, so the question was 'Why the change?'
"Big isn't always beautiful but we lost the legal argument so the only mature thing was to get on with trying to make the new council the best it could be."