By Emanuella Grinberg

CNN

(CNN) -- It's been nearly 152 years since the Confederate Army surrendered to Union forces, ending the American Civil War.

Some Southern states still commemorate those who died fighting for secession from the United States over slavery and states' rights.

State government offices are closed Monday in Mississippi and Alabama for Confederate Memorial Day.

In Georgia the day has been called "State Holiday" since 2015, when Confederate Memorial Day and Robert E. Lee's birthday were struck from the state calendar. The state holiday list says the official holiday is April 26 but will be observed this year on Monday, April 24.

The change in Georgia came amid debate in the South over what to do with Confederate symbols after the killings of nine black parishioners in a Charleston, South Carolina, church, by a white supremacist in 2015.

In some parts of the South, the debate has prompted a counter-effort to honor Southern heritage and preserve symbols of the Confederacy.

A Georgia lawmaker tried to revive Confederate Memorial Day in name in 2017. The proposal, which did not gain traction, made no direct reference to slavery or the Civil War. But it sought to recognize the "four-year struggle for states' rights, individual freedom and local government control."

Mississippi Gov. Phil Bryant issued a proclamation in 2016 declaring April Confederate Heritage Month in his state. Amid backlash, he defended the proclamation, saying "history deserves study and reflection, no matter how unpleasant or complicated parts of it may be," according to his spokesman.

This year he signed another proclamation with similar language and declared April 24 Confederate Memorial Day to "honor those who served in the confederacy."

"It is important for all Americans to reflect upon our nation's past, to gain insight from our mistakes and successes, and to come to a full understanding that the lessons learned yesterday and today will carry us through tomorrow if we carefully and earnestly strive to understand and appreciate our heritage and our opportunities which lie before us," the proclamation reads.

At least one group plans to protest the holiday in Mississippi.

"I'm troubled that in a state made up of 40% people of color, our leadership continues to openly sanction the use of taxpayer funds to endorse a neo-Confederate agenda," Mississippi Rising Coalition President Lea Campbell in a Facebook post promoting the event.

"It is time to move forward. We can be proud Southerners and honor our heritage and the sacrifices made by our ancestors without use of taxpayer funds to promote a racially unjust agenda."