Religious identity was more important than class or race in the US election, analysis published by PRRI suggests.

Christian voters were the core reason for Donald Trump's victory, the research group said, arguing his religious backing was the most significant factor on election night.

The states with the largest white Christian populations were more likely to back Trump. The Republican candidate won 69 per cent of the vote in West Virginia with its 70 per cent white Christian population.

Other states with large Christian populations such as North Dakota (67 per cent), Kentucky (64 per cent) and Missouri (60 per cent) that boast large white Christian populations also went decisively to Trump.

The research highlighted four swing states where Trump did better than expected and pointed out their high white Christian populations. The Republican won Iowa, which is 64 per cent white Christian, Wisconsin, 63 per cent, Ohio, 58 per cent, and Pennsylvania, 57 per cent.

Vermont was one exception to the pattern as 57 per cent are white Christian but only about 33 per cent voted for Trump. PRRI suggested this could be because Vermont was among the least religious states in the country, second to New Hampshire, which also went to Clinton.

"This analysis highlights the power of religious identity and culture in the election," said researcher Daniel Cox.

"Notably, the proportion of white Christians in each of the 50 states is more strongly correlated with support for Trump than is the proportion of white residents without a college degree in the state."