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
Psychic effects of LSD reach their peak about one to three hours following ingestion, when much of the substance has disappeared from the body's major organs, including the brain, though measurable amounts persist in the blood and brain for about eight hours.