Hillary Clinton claimed the Democratic presidential nomination on Tuesday and appealed to the country to reject Donald J. Trump, as a candidate unfit for the presidency.

Mrs. Clinton finished strong in her longer-than-expected primary battle with Senator Bernie Sanders of Vermont, capturing California, according to The Associated Press, and three other states. Mr. Trump did not wait for her to declare victory, lacing into Mrs. Clinton from a golf course he owns in Westchester, and promising to give a speech thoroughly assailing her next week.

But even as the Clinton-Trump battle lines were coming into focus, Mr. Sanders announced from California that he was not prepared to stand down, a potentially irksome development for Mrs. Clinton.

Some of the biggest things we learned on Tuesday:

Clinton’s coalition never cracked

The final Democratic primaries shaped up much like the first round in February: as a contest between Mrs. Clinton’s coalition of women, older voters and nonwhites, and Mr. Sanders’s base of whites, rural voters and young people. That broad matchup budged only a little over the course of the race, handing Mrs. Clinton victory in all the biggest, most populous, diverse and delegate-rich states.