Originally Posted by
Often1
If OP attempts to enter the US across a land border as a Mexican national, he will still be on a watch list for the child support issue. At the border crossing, he will be pulled into secondary and eventually admitted simply because he can't be denied entry as a citizen. But, it will be a lengthy and unpleasant process.
The OP is returning as a US citizen, and generally there is nothing lengthy and unpleasant about the process as long as the OP’s identity and citizenship claims can be readily verified.