The births might be mostly on the border for mothers who waited to enter the US illegally until near time to deliver, but anchor babies are being born all over the US to mothers who entered illegally well before delivery, or before becoming pregnant. Some have had more than one anchor baby in the US.
My problem is with the millions of Mexican women that enter the U.S. for a few days or, in some cases, hours, for the specific purpose of having the baby on U.S. soil and for no other reason.
Now, maybe we need a different combinations of words to communicate the concept. A baby born to an illegal in Seattle, in a hospital, is different than a baby born less than a mile from the Mexican Border in a midwife's home. Born there for the specific purpose of anchoring the family in the U.S.
Both types of babies are U.S. citizens. Both types of babies 'anchor' the family. One is for that specif purpose and none other. That type is 100% anchor baby. I really hope you can see the difference now.