Need information about USA immigration while coming back from Canada

Hello everyone.

Need help

My wife will return to US after Canada PR landing and she’s on H1 visa. She’s flying from Toronto to Phoenix. Could someone please let me know where her immigration will happen? Is it Toronto or Phoenix??

Port of entry procedures happen at the first airport or city, where you enter US. Based on what you say, it would be Phoenix. You can read Port of Entry Process USA