Super Tuesday, the busiest day in the primary campaign, has handed big wins to Democrat Hillary Clinton and Republican Donald Trump.
Of the 11 states that held primaries, both presidential candidates won seven each.
Mrs Clinton found support in black voters in the southern states, as well as female and older voters. Her rival, Bernie Sanders, was victorious in four states.
Mr Trump’s success left Ted Cruz with wins in two states and Marco Rubio, a win in one.
Who were the winners?
Georgia - Democrat: Hillary Clinton, Republican: Donald Trump
Vermont - Democrat: Bernie Sanders, Republican: Trump
Virginia - Democrat: Clinton, Republican: Trump
Alabama - Democrat: Clinton, Republican: Trump
Massachusetts - Democrat: Clinton, Republican: Trump
Oklahoma - Democrat: Sanders, Republican: Trump
Tennessee - Democrat: Clinton, Republican: Trump
Arkansas - Democrat: Clinton, Republican: Trump
Texas - Democrat: Clinton, Republican: Ted Cruz
Minnesota (caucus) - Democrat: Sanders, Republican: Marco Rubio
Alaska (caucus) - Republican: Ted Cruz
Colorado (caucus) - Democrat: Sanders
American Samoa (caucus) - Democrat: Clinton
In pictures: US Elections 2016
In pictures: US Elections 2016
Democratic U.S. presidential candidate Bernie Sanders speaks to supporters after rival candidate Hillary Clinton was projected as the winner in the Nevada Democratic caucuses
Democratic presidential candidate Hillary Clinton takes photos with workers at her campaign office in Des Moines, Iowa
Republican presidential candidate Mike Huckabee, second from left, prays before lunch with supporters at Drake Diner in Des Moines, Iowa
Democratic presidential candidate and former Maryland Governor. Martin O'Malley, speaks during a campaign stop in Waterloo, Iowa
Democratic presidential candidate Bernie Sanders speaks, as his wife Jane O’Meara Sanders looks on, at a campaign event at Iowa State University
Republican presidential candidate Marco Rubio speaks at St. Ambrose University in Davenport, Iowa
Republican presidential candidate Ben Carson speaks at a campaign event at Fireside Pub and Steak House in Manchester, Iowa.
Republican presidential candidate Rick Santorum visiting supporters at a house party in West Des Moines, Iowa
Republican presidential candidate Donald Trump at a campaign event in Cedar Rapids, Iowa
Republican candidate Ted Cruz campaigns at Greene County Community Centre in Jefferson, Iowa
Senator Rand Paul speaks during a Caucus rally at his Des Moines headquarters in Iowa
Republican candidate Jeb Bush speaks at a campaign event in Des Moines, Iowa
Former Alaska Governor Sarah Palin introducing the arrival of Donald Trump during a campaign rally in Cedar Rapids, Iowa
A portrait of Democratic candidate Bernie Sanders at his campaign headquarters in Des Moines, Iowa
Campaign badges on sale ahead of a Trump rally at the Ramada Waterloo Hotel and Convention Centre in Waterloo, Iowa
What is the delegate count now?
Super Tuesday allocates nearly a quarter of the Republican delegates and around a fifth of Democratic delegates.
To become the Democratic presidential candidate, 2,383 delegates are needed. With Mrs Clinton winning the larger states on Super Tuesday, she bagged herself a larger share of the delegates with 457. Mr Sanders won 373.
Republicans need 1,237 delegates to win the party’s nomination. On Super Tuesday, Mr Trump won 203 and Mr Cruz 144.
Trump – 315
Cruz – 205
Rubio – 106
Clinton – 1,055
Sanders – 418
O’Malley - 0
Delegates for each party elect their presidential candidate at party conventions in June.
What do the Super Tuesday results mean for the election?
Mrs Clinton and Mr Trump have made huge strides forward in their respective campaigns, increasing the chance of a battle between the two of them in the November election.
Addressing supporters at a victory rally in Miami, Mrs Clinton said: “It’s clear tonight that the stakes in this election have never been higher and the rhetoric we’re hearing on the other side has never been lower.”
Mr Trump, whose rhetoric and policies have been called divisive by other Republican presidential candidates, said: “Once we get all this finished, I’m going after one person – Hillary Clinton.”
What happens next?
Throughout March, there will be a slew of primaries:
5 March – Kansas, Kentucky, Louisiana, Maine
6 March – Puerto Rico
8 March – Hawaii, Idaho, Michigan, Mississippi
10 March – US Virgin Islands
12 March – District of Columbia, Guam, Wyoming
15 March - Florida, Illinois, Missouri, North Carolina, Northern Mariana Islands, Ohio
22 March – American Samoa, Arizona, Utah