The number of Americans who identify as white and Christian now represents less than 50 percent of the United States population.

A new study says immigrants have driven the decrease along with a growing number of Americans who reject organized religion.

The Public Religion Research Institute, or PRRI, did the study. It questioned more than 100,000 people between January 2016 and January 2017.

It found that Christianity overall remains a large majority. Nearly 70 percent of Americans identify themselves as Christian. However, white Christians -- once dominant -- now make up only 43 percent of the national population.

Forty years ago, about 80 percent of Americans were white Christians.

Today, about 25 percent of Americans do not identify with a single religion, the study found. About 17 percent of Americans now identify as white evangelical Christians, compared to 23 percent 10 years ago.

In the 2016 presidential election, Donald Trump, a Republican, received 80 percent of the votes of white evangelicals.

The PRRI study found that more than one-third of all Republicans say they are white evangelicals. And nearly 75 percent of Republicans identify themselves as white Christians.

By comparison, about eight percent of Democrats call themselves white evangelicals. Almost 30 percent of Democrats identify as white Christians. And 40 percent of Democrats say they have no religious affiliation.

The latest PRRI study also provided state-by-state details. It found that New York is the state with the greatest religious diversity. The southern state of Mississippi has the least religious diversity.

The northeastern U.S. has long been where most of American Catholics live, and the northeastern state of Rhode Island remains the most Catholic state in the country.

However, the Catholic population in the country is shifting, PRRI reports. A majority of Catholics in the U.S. now live in the south or west. The change comes from an increase in Latin American immigrants settling in those areas.