https://www.usps.com/zip4/
After you enter an address, it's under "Mailing Industry Details", shown as "eLOT" (not sure what it stands for)
https://ribbs.usps.gov/index.cfm?page=elot
https://www.usps.com/zip4/
After you enter an address, it's under "Mailing Industry Details", shown as "eLOT" (not sure what it stands for)
https://ribbs.usps.gov/index.cfm?page=elot