Joe Biden claimed victory in Michigan, Mississippi and Missouri – vaulting the former vice-president further ahead of rival Bernie Sanders.
It’s not yet clear who will win the remaining states – North Dakota, Washington and Idaho.
Joe Biden and Bernie Sanders – have won each of the six states that voted today, reports BBC.
These victories mean he tightens his grip on the Democratic race for the White House.
Democrats are choosing a candidate to run against Republican Donald Trump in November election.
Bernie Sanders is his only challenger but his path to the nomination is narrowing.
But some of the best states for Sanders lie ahead tonight.
Idaho and Washington stop voting at 23:00 ET (03:00 GMT)
Votes are still being counted in N Dakota.