Waldo is a city in Columbia County, Arkansas, United States. The population was 1,594 at the 2000 census. Waldo celebrated its 120th year as a city in 2007. The small town was once a booming rail city on the Cotton Belt train route. The city has a rail museum with various displays showing its rail history. The city once bustling with excitement began to waine in population in the 1950s when neighboring Magnolia, Arkansas began drawing industry. Waldo was also home of the fighting Waldo High School Bulldogs basketball teams. Consistently these teams made playoffs and on numerous occasions won the state championship. The legacy of Waldo School will carry on in the community despite its closing in 2005.