Trump, 69, was also leading in Michigan where Ohio Governor John Kasich initially gave him a tough fight.
"Thank you Mississippi!", Trump, the billionaire real estate mogul, tweeted as results came in from the southern state of Mississippi which held Republican primary yesterday.
Clinton, 68, won the Democratic primary contest in Mississippi where she beat her party rival Bernie Sanders, 74.
With Mississippi win, Clinton has grabbed 21 delegates at stake taking her total count to 1134. To win the party's presidential nomination, she needs 2384 delegates of the total 4765.
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Texas Senator Ted Cruz, 45, follows Trump with 300 delegates and Florida Senator Marco Rubio, 44, with 151 delegates.
In addition to Michigan and Mississippi, presidential primaries are also being held in Hawaii and Idaho.
In Michigan, Sanders had earned the support of over half of the Democratic voters as against 47 per cent for Clinton.
In Michigan, Trump was leading by 37.8 per cent of the votes, followed by 26.9 per cent of the Republican votes gained by Kasich.
17 candidates, including Indian-origin Louisiana governor Bobby Jindal, New Jersey Governor Chris Christie and former Florida governor Jeb Bush. The Democratic field, on the other hand, was not as crowded, with just Hilllary Clinton and Senator Bernie Sanders in the race.
CFR explained that at stake in the primary and caucus are a certain number of delegates, or individuals who represent their states at national party conventions. After the primaries and caucuses, most political parties hold national conventions to finalise their choice for their presidential and vice presidential nominees.
Trump officially accepted the Republican party's nomination on July 22. Clinton, the former secretary of state, was officially nominated on July 26 at the Democratic Convention.
Voters will now select presidential electors, who in turn, will vote for the new president and vice president on November 8 through the Electoral College. Electors are apportioned to each of the 50 states as well as to the District of Columbia (also known as Washington, DC).
Therefore, in total, there are currently 538 electors, corresponding to the 435 members of the House of Representatives and 100 senators, plus the three additional electors from the District of Columbia.
It may be noted that electoral members are not members of US Congress.
In contrast, India, which has a multi-party political system, is a constitutional democracy with a parliamentary and not the presidential system of government.
Over 814 million people were eligible to vote in Indian elections, considered the world's biggest democratic exercise where voting was held in 10 stages. India's general elections see a large number of political parties contest the polls. In the 2009 election for instance, 363 political parties took part in the polls.