A 1972 law made the third Sunday in June a permanent national observance; which one?

Best known for his 1828 dictionary, who also wrote textbooks on science, grammar and history? Best known for his Pooh stories, which author published "The Red House Mystery" in 1922? Which Supreme Court justice was nicknamed "the Great Dissenter," though he dissented in relatively few cases? Which city has been Delaware's capital since 1777, though it wasn't incorporated as a city until 1929? Which Washington, D.C., university, founded in 1867, didn't have its first Black president until 1926? Which president, badly defeated in 1932, later led two commissions to reorganize the executive branch? Which slugger, nicknamed "Mr. October," holds the major league career record for strikeouts by a batter, with 2,597? Which future president graduated 64th of 112 in his 1935 prep school class but was voted "most likely to succeed"?