Adams's prediction was off by two days. From the outset, Americans celebrated independence on July 4, the date shown on the much-publicized Declaration of Independence, rather than on July 2, the date the resolution of independence was approved in a closed session of Congress.
LSD effects usually last for 12 hours. But LSD can stay in your system for up to 5 days after use. More on the bioavailability, half life and detection window
Citation: Last J. LSD Does Not Stay in your Body Forever. Erowid.org. May 2006; erowid.org/chemicals/lsd/lsd_myth1.shtml. There is an often circulated myth that once you have taken LSD, it remains in your body forever.