Martin Luther King Jr. Day (officially Birthday of Martin Luther King, Jr.,^[1] and sometimes referred to as MLK Day) is a federal holiday in the United States marking the birthday of Martin Luther King Jr. It is observed on the third Monday of January each year. Born in 1929, King’s actual birthday is January 15 (which in 1929 fell on a Tuesday). The holiday is similar to holidays set under the Uniform Monday Holiday Act. The earliest Monday for this holiday is January 15 and the latest is January 21.

King was the chief spokesperson for nonviolent activism in the Civil Rights Movement, which protested racial discrimination in federal and state law. The campaign for a federal holiday in King’s honor began soon after his assassination in 1968. President Ronald Reagan signed the holiday into law in 1983, and it was first observed three years later. At first, some states resisted observing the holiday as such, giving it alternative names or combining it with other holidays. It was officially observed in all 50 states for the first time in 2000.

Text and homepage image from Wikipedia.

From the city website:
City Offices Closed Monday, January 16th for MLK Day

On December 20, 2022, the City of Whitewater Common Council approved Martin Luther King, Jr. Day as an additional holiday for city employees. All city offices will be closed on January 16th, but citizens who need police assistance may use the after hours call button in the Municipal Building Whitewater Street vestibule or may call the non-emergency phone number at 262-473-0555 option 4. For all emergencies, please call 9-1-1.