Sheffield's recently unveiled Women of Steel tribute was subject to the gagging order, as was one of the city's newly installed elephants in a "seen but not herd" demo.
Barnsley was also targeted amid continued campaigning for a regional parliament.
Yorkshire Party are at the forefront of northern calls for local say on issues including transport, education and healthcare.
Members of what was Yorkshire First symbolically covered mouths of well known statues countywide as part of the outcry.
Party acting leader Stewart Arnold said: "It's appropriate today, Yorkshire Day, to draw attention to the fact Yorkshire has no 'voice' in the same way Scotland, Wales and even London have when it comes to running its own affairs.
"We want the opportunities here that would make a difference to our lives, starting with real educational investment. After all, school funding per pupil in London is more than double that of those in Yorkshire".
He continued: "Meanwhile, Scotland has seen the reopening of railways lines closed for over 50 years and has a moratorium on the granting of fracking licences.
"The common denominator in this is, of course, that in both London and Scotland decisions can be made locally which have a real and positive impact on people's lives, the economy and the environment.
"Yorkshire with its five million people has none of this. It needs a voice," he added.
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