Seventeen councils in Yorkshire have said for the first time they want to unite behind a devolution deal.
A "coalition of the willing" is being called for by several leaders as part of a Yorkshire Day declaration.
Despite a range of proposals, councils have so far failed to agree a pan-Yorkshire deal.
Sheffield and other councils in South Yorkshire and the north Midlands agreed a government deal for the Sheffield City Region.
However, the election of a mayor for the region was postponed following a court ruling about a flawed consultation process.
Following the deal, Doncaster and Barnsley councils have also said they were looking at a whole Yorkshire devolution proposal.
Analysis by James Vincent, BBC Look North political editor.
This is a nice headline for Yorkshire Day, but it feels very unlikely to happen.
The government has already said that it does not like the idea of a deal for the whole of Yorkshire, and even if the county does come together, South Yorkshire will still be electing its own mayor next year.
The original idea for devolution was to give "travel to work" areas more powers; places gathered around a natural commuter hub. So Barnsley, Doncaster, Rotherham and Chesterfield were tied to Sheffield. I don't think many people are commuting from Scarborough for work in Sheffield.
North Yorkshire is very different to South Yorkshire, and different against to West and East Yorkshire. Though a novel thought to bring the whole county together on a day created to stick two fingers up at the government, it feels like a nice idea with very little detail attached.
The councils that have made the 1 August declaration are: Barnsley, Bradford, Calderdale, Craven, Doncaster, East Riding of Yorkshire, Hambleton, Harrogate, Hull, Kirklees, Leeds, North Yorkshire, Richmondshire, Ryedale, Scarborough, Selby and York.
It does not include Sheffield and Rotherham.
A declaration said: "Today is Yorkshire Day and therefore it seems right to talk today about our county, its ambitions and our identity.
"The county is big enough and bold enough to want to carve out its own destiny.
"The leaders agreed unanimously to form a 'coalition of the willing', working towards securing a single ambitious devolution deal for the Yorkshire authorities and areas wanting to work together on this basis."
There are plans for the councils to meet again in September to decide how to take the negotiations forward.
- Has a population of more than 5.3m people
- It is divided into a number of different councils across North Yorkshire, South Yorkshire, West Yorkshire and East Riding of Yorkshire
- Leeds is the largest city in Yorkshire with a population of about 775,000, followed by about 570,000 in Sheffield and Bradford with about 530,00
- There are eight cities in the county with more than 100,000 people
Source: Country digest
- Selby District Council
- Hull Council
- Scarborough Borough Council
- Hambleton District Council
- East Riding of Yorkshire Council
- York City Council
- Kirklees Council
- Calderdale Council
- Ryedale District Council
- City of Bradford Metropolitan District Council
- Richmondshire District Council
- Leeds City Council
- Doncaster Metropolitan Borough Council
- Craven District Council
- North Yorkshire County Council
- Barnsley Metropolitan Borough Council