By the time the campaign tracked down the small-city Indiana mayor, Bill Clinton was in a lather. Senator Hillary Rodham Clinton had lost the North Carolina primary that evening and was eager to offset it with a win in Indiana. But a vote-counting delay in one county threatened to rob her of a prime-time victory speech.

The Clinton campaign called a supporter for help. “I’ve got an angry president here and a candidate who wants to know whether or not she won,” a local campaign representative told the mayor, Thomas McDermott Jr. of Hammond, Ind. Mr. McDermott could hear Mr. Clinton railing in the background. “It’s not very often you basically have a former president yelling at you to get the numbers out,” he recalled.

The yelling was for naught. Mr. McDermott said he had no control over the vote count and, in the end, the late results cemented a negative narrative for an evening dominated by the North Carolina defeat with little attention focused on the eventual Indiana victory. The night of May 6 became the moment that Mrs. Clinton’s desperate comeback bid for the Democratic presidential nomination finally crashed against the reality of delegate math. All she had left was the perception of momentum, and suddenly, that was gone.

Hers was a campaign of destiny that fell achingly short, garnering nearly 18 million votes in her quest to become the first woman to hold the presidency. “Although we weren’t able to shatter that highest, hardest ceiling this time, thanks to you, it’s got about 18 million cracks in it,” Mrs. Clinton said as she ended her campaign on Saturday.