Tuesday's primary voting laid bare a profound racial and ethnic divide among Democratic voters, with African-Americans overwhelmingly preferring Barack Obama, while Latinos largely favoured Hillary Clinton.
Figures from Associated Press exit polls show Obama won eight in 10 black voters except in Clinton's home state of New York, while Clinton won six in 10 Hispanics. That pattern suggests that the first-term Illinois senator's strong appeal among African-Africans - first on display in the South Carolina primary last month - is more widespread.
It also indicates that Clinton is not the automatic heir to the wide popularity her husband enjoyed among black voters while he was president.
On the other hand, Tuesday's contests were the first to feature states, such as California, with large Hispanic populations, and they selected Mrs Clinton by smaller but consistent margins.
The divergent choices by minority voters reflect broad issues of loyalty and identity, observers said, rather than specific differences in the candidates' stances on issues.
"There is so little distance between the policies, it comes down to personality, style and name recognition," said Arturo Vargas, executive director of the Los Angeles-based National Association of Latino Elected and Appointed Officials.
"No one has said, 'This is the black Democratic agenda, the Latino Democratic agenda," Mr Vargas said. "This is just, who do people know, who do they identify with, who are they comfortable with?"
Mr Obama's strong appeal among black voters surfaced less than two weeks ago in South Carolina, where exit polls indicated that he defeated Mrs Clinton by a margin of 4 to 1 among that segment of the electorate. "The South Carolina primary was decisive," said David Bositis, senior political analyst at the Joint Centre for Political and Economic Studies. "It sealed the deal for African-Americans on Obama."
At the time of that primary, some political analysts contended that Mrs Clinton's support among African-Americans had eroded sharply after Bill Clinton derided Mr Obama's claim of long-held opposition to the Iraq war as a "fairy tale", and after Senator Clinton suggested that the Rev Martin Luther King's vision only "began to be realised" after President Lyndon Johnson passed the Civil Rights Act in 1964.
On Tuesday night, however, analysts attributed Mr Obama's wide margins among black voters to his own candidacy. "There is a sense of pride in who he is," said Marc Morial, president of the National Urban League. "His message of transformation and change is resonating."
Mr Obama is also benefiting from a longstanding pattern in which "African-American voters . . . tend to coalesce in big elections," Mr Morial said. "It's the pursuit of a collective agenda."
Given that Mr Obama spent comparatively little time campaigning in western states with big Latino populations, Mr Bositis said it was notable that the Illinois senator picked up as much Hispanic support as he did, drawing more than one-third of Latinos' votes in Arizona and California. "In his campaign, that is really good," Mr Bositis said.
Still, Mrs Clinton benefited from the long allegiance Hispanics have felt toward the Clintons since her husband was in the White House.
"There is a real affection for the Clinton administration and a real familiarity with Senator Clinton," said Cecilia Munoz, senior vice-president for policy at the National Council of La Raza. In addition, Ms Munoz said, Mrs Clinton "got support of the big figures in the Latino political establishment quite early. So she has really terrific surrogates and they have been on board with her for a long time."