President-elect Joseph R. Biden Jr. has narrowly won Arizona, capturing the state’s 11 electoral votes and strengthening his Electoral College margin as President Trump continues to make baseless attacks on the vote counts favoring Mr. Biden.
Mr. Biden, whose margin in Arizona is currently about 11,000 votes, or 0.3 percentage points, is the first Democratic presidential candidate to carry the state since President Bill Clinton in 1996. Four years ago, Mr. Trump won the state by 3.5 percentage points.
That Arizona — the home of the late Senator John McCain and Senator Barry Goldwater, a founder of the 20th century conservative political movement and the 1964 Republican presidential nominee — was in play for Democrats at all is remarkable. Before the state voted for Mr. Clinton, the last Democrat it had supported for president was Harry S. Truman in 1948.
Mr. Biden’s win underscored a profound political shift in Arizona, a longtime Republican bastion that has lurched left in recent years, fueled by rapidly evolving demographics and a growing contingent of young Hispanic voters championing liberal policies.
Last week, the Democratic challenger Mark Kelly defeated the state’s Republican senator, Martha McSally, in a special election, making Mr. Kelly and Senator Kyrsten Sinema the first pair of Democrats to represent Arizona in the Senate since the 1950s.
The Arizona victory brings Mr. Biden to 290 electoral votes, 20 more than the 270 required to take the White House.