The UK's next prime minister has been urged to end "damaging uncertainty" by giving their backing to HS2 lines north of the Midlands and a new line linking Liverpool with Hull.
Council leaders and elected mayors have jointly addressed a letter to each of the candidates in the Conservative Party leadership race to seek clear commitment to the projects.
Only the first phase of the £56bn HS2 project between London and Birmingham has so far been approved and Transport Secretary Chris Grayling is being urged to win over sceptics before parliament debates links to Manchester and Leeds next year.
The government is considering plans for the £39bn east-west Northern Powerhouse Rail (NPR) line, dubbed the "Crossrail of the North".
The letter said it was "only through the full delivery of both HS2 and NPR that the North can see truly transformative benefit".