She said people approached him after to shake his hand.
But when Clancy uploaded the video to her Facebook as she was leaving the Walmart, she had no idea it would get thousands of shares, and hundreds of thousands of views within days.
"Here it is, Memorial Day," she said, "(and) he was there singing 'God Bless America', and it was a feeling like, 'Oh my god, people just really still love America.'" According to her husband, more than 75 people stopped to watch the man, who Facebook commentators identified as Raymond Greene, sing while sporting a bald eagle and American flag across his shirt.
After he finishes singing, the crowd can be heard in Clancy's video cheering and clapping.
Although Greene did not respond to Inside Edition.com's attempts to contact him, witnesses have speculated that he is a veteran himself.
She said she immediately turned on her phone to begin recording, and followed his voice.
"It was really overwhelming hearing this man sing at a Walmart," said Clancy, who told Inside that many members of her family are involved in the U. Armed Forces, dating back to her grandfather, who served in World War II.