The Clinton campaign will point out from time to time that it is not unusual for primary races to last into the summer. Just last week, Bill Clinton said this in North Carolina:
"All these people that tell you, 'Aw we oughta shut this thing down now the Democrats are so divided' that's a bunch of bull. I didn't get enough votes to be nominated until June the 2nd, 1992."
As ABC News reports, that's somewhat misleading. While it's accurate that Clinton secured the delegates he needed to win the nomination on the night of the California primary — June 2, 1992 — he effectively wrapped up the nomination after Senator Paul Tsongas dropped out following the Illinois primary.
That was in late-March. Right around now.