I'm still looking to find the part of the US Code that defines "school zone", but it's the property on which a grade 1-12 school sits (K-12 on tribal lands) + 1000' (apx. 3 blocks, 1/5 of a mile) from the edge of the property in all directions.
So the universities are NOT included, but your car on the street in front of the high school is.
As you read the law (below) you'll notice that when you're on private property you're exempt.
If you have a license from that state, you're exempt.
If it's unloaded & in a locked case, you're exempt.
Some states have more stringent laws, so search your state code.
(For example, WI says there's a difference between the 1000' magical bubble and the grounds/buildings of the school.)
Notice also the underlined clause - I can't recall any other law with such an "out". So never go looking for schools on Google maps. Part of the elements of the crime is that the prosecutor has to prove beyond a reasonable doubt that you knew or reasonably should have known you were within 3 blocks of a school.
18USC922 (q) (2)
(A) It shall be unlawful for any individual knowingly to possess a firearm that has moved in or that otherwise affects interstate or foreign commerce at a place that the individual knows, or has reasonable cause to believe, is a school zone.
(B) Subparagraph (A) does not apply to the possession of a firearm—
(i) on private property not part of school grounds;
(ii) if the individual possessing the firearm is licensed to do so by the State in which the school zone is located or a political subdivision of the State, and the law of the State or political subdivision requires that, before an individual obtains such a license, the law enforcement authorities of the State or political subdivision verify that the individual is qualified under law to receive the license;
(iii) that is—
. . . . . (I) not loaded; and
. . . . . (II) in a locked container, or a locked firearms rack that is on a motor vehicle;
(iv) by an individual for use in a program approved by a school in the school zone;
(v) by an individual in accordance with a contract entered into between a school in the school zone and the individual or an employer of the individual;
(vi) by a law enforcement officer acting in his or her official capacity; or
(vii) that is unloaded and is possessed by an individual while traversing school premises for the purpose of gaining access to public or private lands open to hunting, if the entry on school premises is authorized by school authorities.