How to interpret Immigration processing port codes on older Green Cards

[William Shaw]

My mother immigrated in the early 50s from Canada to marry a Wyoming cowboy, raise a family, and take up the practice of nursing. I have her old Green Card with all the arrival/processing location information in two codes. An internet search floods my screen but I'm unable to find a lookup source for those codes, to identify where she arrived in the US.

Would someone be so kind as to point me toward an authoritative index?

Thank you.

[William Shaw]

Interesting. According to Immigration and Naturalization Services Genealogy branch, they are swamped with requests and have a six month backlog, so they sent me to Freedom Of Information, which responded in days, that her record is not available.

[thomprod]

To be correct, your mother EMigrated FROM Canada and you're trying to find out which US port she IMMigrated TO. Assuming she was a Canadian citizen and then later became a US citizen, that information would be on her Petition for Naturalization and also on another document called the Certificate of Arrival. I've found scans of many of these documents on Ancestry.com.