The number of United States-born children of illegal aliens in ten states is more than four times the total population of Boston, Massachusettes, data reveals.

The U.S.-born children of illegal aliens are commonly known as “anchor babies,” as they “anchor” their illegal alien and noncitizen parents in the U.S. when they are granted immediate birthright citizenship.

There are at least 4.5 million anchor babies in the country, a population that exceeds the total number of annual American births, as about 300,000 anchor babies are born every year, exceeding the total number of American births in 48 states.

Currently, the U.S. and Canada are the only developed nations in the world that offer unrestricted birthright citizenship.

Data compiled by the Migration Policy Institute finds there are more than 2.9 million anchor babies under the age of 18 years old in these ten states: California, Texas, New York, Florida, Illinois, Georgia, North Carolina, New Jersey, Arizona, and Washington.

The anchor baby population in these ten states, alone, is more than four times the size of Boston’s population — where about 685,000 residents live. The anchor baby population in these ten states is also more than six times the population of Miami, more than five times the population of Wyoming, and about 44 times the population of Portland, Maine.