Upvote:4
US social security numbers are permanent.
https://www.ssa.gov/history/hfaq.html
Q20: Are Social Security numbers reused after a person dies?
A: No. We do not reassign a Social Security number (SSN) after the number holder's death. Even though we have issued over 453 million SSNs so far, and we assign about 5 and one-half million new numbers a year, the current numbering system will provide us with enough new numbers for several generations into the future with no changes in the numbering system.
While this does not absolutely prove I am right, it indicates that SSNs are assigned to a person and never reassigned, therefore your number will be reused when you re-immigrate to the US.