Hull is the eighth most affordable area in England to buy a house, according the research by the TUC.
But the ratio of house prices to average earnings rose from 2.18 times in 1997 to 3.92 in 2013.
It means the city is the only place in Yorkshire where house prices are less than four times the average salary.
Of larger towns and cities, Hull is behind only Stoke-on-Trent and Derby.
In the East Riding, the affordability ratio rose from 3.26 to 5.77.
The most affordable place to buy a house is Copeland in Cumbria.
The least affordable area is Kensington and Chelsea, with a mind-boggling affordability ratio of 32.39.
Harrogate is the most expensive area to live in Yorkshire, while previously "affordable" areas of the region, such as Bradford and Rotherham, are now seeing prices at least 4.5 times the average wage.
The TUC said that ratio should be seen as significant because the Bank of England has told financiers to limit the number of mortgages offered at more than 4.5 times an applicant's salary.
TUC regional secretary Bill Adams said: "Yorkshire has always had its blackspots in terms of housing affordability but by and large houses and flats in most parts of the region were within reach of local people.
"We need to build more homes to get house prices back under control.
"With interest rates low, now is the perfect time for an ambitious programme of home-building, which would also help tackle local unemployment problems."
Jon Myers, a director of East Yorkshire estate agent Quick and Clarke, said he was "staggered" to hear Hull's prices were the lowest in the region.
He said: "People seem to pick on Hull when it's absolutely unwarranted.
"How can the report make such a sweeping statement? You've got to question where they get these figures from. When you look at some areas like Willerby they can be pretty expensive.
"It's affordable and you could get buyers coming in here but this doesn't do Hull any benefits because it's saying Hull is a cheap place. In actual fact, it's not."
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