For several hours Wednesday, senators from both parties spoke to pay tribute to Mikulski, D-Md., The Baltimore Sun reported.
"Marylanders understand longevity records. We're very proud of our Cal Ripken," Cardin, Maryland's junior senator, said. "Senator Mikulski's, like Cal Ripken's, legacy is what she has done in office, not the length of it."
Mikulski entered the House of Representatives in 1976 and the Senate in 1986. On Saturday, she beat the previous record longest-serving woman, Rep. Edith Nourse Rogers of Massachusetts, who died in 1960.
"The Senate used to be a very lonely place for women, but Senator Mikulski changed that," Sen. Barbara Boxer of California said.
Mikulski paid tribute to her parents when she spoke in front of her colleagues.
"I still am the young girl who watched her father open his grocery store and say, 'Good morning, can I help you?'" Mikulski said.
Notable deaths of 2014 [PHOTOS]