Missing Comma After Introductory Clause With Date

Dependent introductory clauses which include a date should be offset by a comma. The date can be a year or the date of the month.

In 1989, he graduated from high school.

By the 1960s, most households had a television set.

During the 1800s, canned foods were becoming popular.

Since November 15th, we’ve raised more than a thousand dollars for charity.