Many Americans will mark the 60th annualon Thursday - and this year, unlike in recent history, there is little national controversy surrounding the occasion.
Last April, Wisconsin federal judge Barbara Crabb, arguing that it "goes beyond mere 'acknowledgment' of religion because its sole purpose is to encourage all citizens to engage in prayer, an inherently religious exercise that serves no secular function in this context."
The ruling ignited ire from a number of lawmakers, including Texas Republican Lamar Smith, who wondered, "What's next? Declaring the federal holiday for Christmas unconstitutional?"
The White House appealed the decision, arguing that the National Day of Prayer merely acknowledged the role of religion in the United States. And President Obama issued a proclamation recognizing the day despite the legal controversy.
Still, some wondered about the future of the National Day of Prayer.
On April 14, 2011, however, a federal appeals court panel.
"This is a poignant moment for the National Day of Prayer because one year ago we met right here with a shadow hanging over the National Day of Prayer," said Dr. James Dobson, a prominent evangelical Christian, in an interview with the Christian Post.
On April 29, Mr. Obama recognized the National Day of Prayer for 2011, noting in his proclamation that "Prayer has played an important role in the American story and in shaping our Nation's leaders."
But not everyone is celebrating the designated day of prayer: Rep. Pete Stark (D-Calif.) recently issued his own proclamation recognizing the National Day of Reason, which is celebrated by many atheists as an alternative event.
"I encourage everyone to join in observing this day and focusing upon the employment of reason, critical thinking, the scientific method, and free inquiry to the resolution of human problems and for the welfare of human kind. It is the duty and responsibility of every American to promote the development and application of reason," Stark said in a statement on the floor of the House of Representatives.
"Reason and rational thinking have made our country great," he said. "The Constitution also contains a strong separation of church and state, making it clear that government should continue to be built on reason."