Here is a perfect example of incorrect information that found it's way into a filing with the Federal Court in Washington D.C.
23. At least 15 states prohibit the open carrying of weapons in public (Connecticut, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Maryland, Massachusetts, Minnesota, New Jersey, New York, Rhode Island, South Carolina, and Texas). NRA, PRACTISING LAW INSTITUTE:MUNICIPAL LAW INSTITUTE 2009, at 207–211.
The case where this incorrect fact was submitted to the courtis:TOM G. PALMER, et al. vs. DISTRICT OF COLUMBIA, et al., Civil Action No. 09-01482 (HHK)
Here is the actual PDF copy of the document filed with the court by attonreys representing our Nation's Capitol where they cite an NRA publication, read item 23 listed in this document and judge for yourself!!