Martin Luther King Jr. Day is a federal holiday, but some shipping and delivery services may still be operational. Here's what we know.

The holiday falls on the third Monday of January. A bill to make Martin Luther King Jr. Day a federal holiday was introduced on April 8, 1968 — four days after King was assassinated, according to the National Museum of African American History and Culture.

While most government functions will not be operating on Monday, most grocery stores, big box stores and restaurants will remain open. Major chain stores such as Target, Costco, Walmart, The Home Depot, Jewel-Osco and Mariano's will remain open on the holiday.