This is an easy one. The 'Anchor baby' is a US Citizen; and he/she is welcome to come to the USA anytime they wish .... when they are an adult. For the time being; they must live with their parents, in the country that their parents are a citizen of.
Just because a baby is a US Citizen, doesn't mean that Mom, Dad and 99 of their dependants get a free trip here. That would be insane.
There are some in the U.S. Congress who have tried repeatedly to pass a simple amendment to the Immigration and Nationality Act (8 U.S.C. 1102).
That same bill, has been re-introduced in the 109th Congress as H. R. 698. The express purpose of the bill is "to deny automatic citizenship at birth to children born in the United States to parents who are not citizens or permanent resident aliens."(29)