Waelder is on State Highway 90, two miles north of Interstate Highway 10, eighteen miles north of Gonzales in northern Gonzales County. It was named for Jacob Waelder, a prominent San Antonio attorney. The town was surveyed into town lots in 1874 by agents of Thomas Wentworth Peirce, president of the Galveston, Harrisburg and San Antonio Railway, as one of a chain of depots between Houston and San Antonio. Many of Waelder's first residents, businesses, doctors, churches, and schools relocated from Hopkinsville, five miles to the north. The Hopkinsville Masonic Lodge moved to Waelder in May 1878. By the early 1880s Waelder had saloons, a livery stable, a restaurant, a photograph gallery, two steam mills, a brickyard, and schools. Robert Johnson, a blacksmith, was the first Black businessman in Waelder. Henrietta "Hettie" Manlove Cunningham was one of the first teachers and the first woman pharmacist licensed by the Texas Pharmaceutical Association in 1888. The Belle Eden School for Black children was in operation in June 1879 under the direction of Reverend O. E. Perpener. On June 26, 1886, the Colored Masonic Lodge of Waelder was organized; Anderson Price, a well-known African-American landowner in Gonzales County, had donated the land for the lodge. Waelder was first incorporated in 1887; E. W. Walker was the first mayor. "Squire" Walker also served as justice of the peace of Precinct Three for fifty-four years, holding court first in Hopkinsville and later in Waelder from 1866 through 1922. The corporation of the town was abolished on May 7, 1894, and was reestablished on March 25, 1913, with a mayor and five aldermen, as it remains today.
The cattle industry played an important role in the growth of Waelder, and many herds from the area were sent up the trail. Waelder had trouble with fence cutting, and in 1883 Capt. George Scott, with a group of Texas Rangers, was ordered to the area to restore order. Corn and cotton have been principal crops, and later poultry production became an important industry. The town continued as a railroad shipping depot until the 1950s. The depot was closed, and the last train stopped at Waelder on June 7, 1958. R. L. Miller's General Merchandise Store, a landmark in the town, first opened in Hopkinsville in 1866, moved to Waelder in 1874, and remained in business until December 14, 1979. In 1980 the Miller's store building was sold to the J-Bar-B Food Company, which in 1989 was Waelder's only industry and largest employer. The population in Waelder saw a steady decline during World War II. Many citizens left to join the armed forces, and others moved to larger Texas cities to seek better employment. Waelder had several businesses on State Highway 90, but the number declined when Interstate Highway 10 was built two miles south of the town. The population of Waelder in 1950 was 1,276 and in 1980 numbered 942. In 1990 it was 745. The population reached 947 in 2000 and 1,065 in 2010.