Originally Posted by B747-437B
Some INS/BCS officers can be incredibly anal and I have even heard stories about people being subjected to Expedited Removal for standing in the wrong line (evidently entering the US citizens line, even in error, can be considered "misrepresentation of citizenship"). Better not to take the chance of having her AP cancelled by an officer on a power trip and simply stick with the longer line until the PR comes through.
Nah, that sounds a little over board. The visitor line suggestion is right on, however. I do know someone who ended up in "special processing" which is booth 1 at ORD or DTW or MSP, can't remember which one. This was because the officer at the original line did not have the proper stamp.