Historical clue formulations

• It borders this many other states — 2018-04-19
• With 24-Across, why a Midwest river has so many tributaries? — 2011-01-16
• ___ Valley Conference in college sports — 2007-09-27
• "___ Waltz," which begins "Hush-a-bye, ma baby, slumbertime is comin' soon" — 2007-03-24
• Ship on which W.W. II ended, 9/2/45 — 2001-04-10
• Truman's home state — 1999-05-18
• Famous surrender site — 1996-03-30