Having just moved to MN (thanks to all for the moving to MN advice), I can't help but notice the recent proliferation of NO Firearms signs all about the state.
This is very amusing to me.  Who do they think they are deterring?  The law abiding concealed carry owner?  
Similar signs appeared in builings in TX after the concealed carry was passed there.  IMHO these signs give tourists and others new to the state the impression (wrongly) that these signs are needed to keep out packs of armed thugs and that an environment of lawlessness pervades the state.
This can not be good for tourism.  I guess their anti-gun ideology is more imprortant to them than their business is.  Just my .02.

Number one, how would they know you're carrying and number two, what exactly could they do about it if they found out other than ask you to leave?

Ignore those silly signs.

When possible, don't patronize those businesses that hang anti-gun signs.  Then let them know that you don't go there anymore and the reason why.

The signs are brought to you by the indigenous liberal scumbags. The signs essentially say "Hey lunatics, this is a victim rich designated slaughter zone."

Sad state of affairs.