Washington, May 16 (IANS): International migration is projected to surpass natural increase as the principal driver of US population growth by the middle of this century, the first time in two centuries, the US Census Bureau estimates.

According the three latest series of projections, the shift in what drives US population growth is projected to occur between 2027 and 2038, depending on the future level of international migration, reported Xinhua.

This would mark the first time that natural increase was not the leading cause of population increase since at least 1850, when the census began collecting information about residents' country of birth.

"Our nation has had higher immigration rates in the past, particularly during the great waves of the late 19th and early 20th centuries," said Thomas Mesenbourg, the Census Bureau's senior adviser Wednesday.

He noted that the latest "projected milestone" reflects the mix of the nation's declining fertility rates, the aging of the baby boomer population and continued immigration.

Higher international migration would mean a faster growing, more diverse, and younger US population, said the agency.

Among the latest projections, the total US population in 2060 ranges from 392.7 million to 442.4 million. The net international migration in 2012 ranges from 702,000 to 747,000, while the projected figure for 2060 ranges from 824,000 to 1.6 million.