Answered By: Daniel Dylla Last Updated: Feb 23, 2016 Views: 22
According to the Purdue Online Writing Lab, it would look like this:
U.S. Constitution. Art. I, Sec. 2
U.S. Constitution. Amend. XIV, Sec. 2
The Purdue Online Writing Lab is a useful resource for MLA and APA citation questions. The link also explains how to do a parenthetical citation for the Constitution (and much more).