I-94 arrival records will be alphanumeric beginning May 2019

U.S. Customs & Border Protection has announced that beginning in May 2019, I-94 records will contain a letter of the alphabet in the 10th position of the 11 character sequence.  I-94 records will continue to have 11 characters.  The first nine will be numbers, the 10th character will be a letter, and the 11th character will be a number.  The change is due to the agency exhausting available numeric sequences.  

The CBP announcement can be found at:  https://www.cbp.gov/travel/international-visitors/i-94