Hull and Huddersfield are the only Yorkshire towns and cities where less than half of their exports go to European Union countries, according to Centre for Cities.
However, the figures also show Yorkshire’s poor export record in comparison to other parts of the country.
The value of exports per worker in every Yorkshire town and city is below the national average of £15,960.
Centre for Cities chief executive Alexandra Jones said: “Securing the best possible EU trade deal will be critical for the prosperity of cities in Yorkshire, and should be the Government’s top priority as we prepare to leave the single market and potentially the customs union.
“While it’s right to be ambitious about increasing exports to countries such as the US and China, the outcome of EU trade negotiations will have a much bigger impact on places and people up and down the country.
“It’s also important that the Government aims to reach trade agreements covering as many sectors as possible, rather than prioritising deals for high-profile industries based in a small number of places.”
Hull emerges as the only one of the 62 towns and cities studied by Centre for Cities that sends a greater share of its exports to the US than the EU.
Doncaster and Wakefield are the most dependent on European markets, sending 57 per cent of their exports to EU countries.
Sheffield Hallam MP Nick Clegg, the Liberal Democrats’ Brexit spokesman, said: “It is not surprising to see that more than half of Sheffield’s exports go to our closest neighbours in the EU.
“The government’s reckless plans to take Britain out of the single market will hit local businesses hard when they are no longer able to export freely to their biggest customer.
“Whether they voted Leave or Remain, no one voted to make our country poorer and to damage local businesses.”