I’m writing to warn fellow SurvivalBlog readers that there is a huge proviso for those wishing to open carry firearms in states where it is lawful to do so.
I recommend reading the Wikipedia page on Gun-Free School Zones Act (GFSZA) of 1990.
Some key excerpts form that web page follow:
Pursuant to 18 U.S.C. § 921(a)(25) the term “school zone” means—
(A) in, or on the grounds of, a public, parochial or private school; or
(B) within a distance of 1,000 feet from the grounds of a public, parochial or private school.
Pursuant to 18 U.S.C. § 921(a)(26) the term “school” means a school which provides elementary or secondary education, as determined under State law.
Prohibition of unlicensed carry
Most states allow some form of unlicensed carry by people without criminal convictions. This may be open-carry, vehicle-carry, or concealed carry without the need for a permit. The Federal GFSZA prohibits unlicensed carry by making it a federal crime for an unlicensed individual to travel into a “Gun Free School Zone unless they meet one of the other criteria defined in Section ‘B’.”  The large number of K-12 schools in developed areas makes it difficult for an individual to travel any distance without entering a Gun Free School Zone.
18 U.S.C. § 924(a)(4) establishes the penalty for violating GFSZA:
Whoever violates the Act shall be fined not more than $5,000, imprisoned for not more than 5 years, or both. Notwithstanding any other provision of law, the term of imprisonment imposed under this paragraph shall not run concurrently with any other term of imprisonment imposed under any other provision of law.
Note: A conviction under the GFSZA will cause an individual to become a “prohibited person” under the Gun Control Act of 1968. This will bar them from legally owning firearms for the rest of their life.
JWR Adds: The Constitutionality of that law is doubtful. (It was already overturned once by the Supreme Court once, only to be reenacted by Congress in slightly different form.) But unless or until it is overturned, I would recommend that before open carrying near any schools that readers either: A.) obtain a concealed carry permit or B.) that they only carry pre-1899 antique guns, which are not considered “firearms” per Title 18 U.S.C. (Even so, be prepared to be stopped and challenged by under-informed law enforcement officers, and hence prepared to to prove that you are either a permit holder or that the particular gun that you are carrying had a frame or receiver that was manufactured in or before 1898.)
Readers are also warned that state and local laws vary widely, so do your homework before you exercise your right to be armed.