Carl Hilmar (Hilmer) Guenther, pioneer miller, son of Carl Gottfried and Johanne Rosina (Koerner) Guenther, was born at Weissenfels on the Saale River in Germany on March 19, 1826. He was one of eight children, the first of this line to migrate to America. In 1848 he traveled to New York and then to Wisconsin and down the Mississippi River before returning to Germany for a few months. Around 1851 he returned to America, landed in New Orleans, and traveled to Indianola, Texas. From Indianola he trudged the 250 miles to San Antonio beside a provision wagon. In San Antonio he heard of the need for a gristmill and flour mill in Fredericksburg, so he traveled there and built his first mill on Live Oak Creek nine miles west of Fredericksburg. He excavated the mill race with a pick and shovel and designed and made the waterwheel and gears of native woods. After a flash flood swept away an incomplete dam, he rebuilt from the ground up. In 1855 he married Dorothea (Dorathea or Dorethea) Wilhelmine Henriette Pape in a Lutheran ceremony in the first community church. They had seven children. Guenther was Fredericksburg justice of the peace in 1856. After two years of drought had depleted the crops and water supply, the family moved to San Antonio in 1859. By October of that year, on the bank of the San Antonio River at the foot of King William Street, Guenther had built the first flour mill in the city. In 1898 his mills were incorporated as C. H. Guenther and Son; the name was later changed to Pioneer Flour Mills. Guenther also established a small ice plant called the Southern Ice Company (later Southern-Henke Ice Company). He helped found San Antonio's German-English School and held membership in the Beethoven Männerchor, the Arbeiter Verein, and the Casino Club, San Antonio's first social club and theater. Guenther and his descendants constantly improved and enlarged the mills. By 1900 their 200-horsepower engine was the largest in the city. Guenther died on October 18, 1902, in San Antonio and was buried beside his wife in City Cemetery No. 1.
In 1987 Pioneer Flour Mills, on East Guenther Street, was still family owned and operated. Guenther's home, built in the Texas Vernacular style and located near the mill on the San Antonio River, was one of the first houses constructed in what became the King William Historic District. In 1988 extensive renovations were completed, and the house, still family-owned, was opened to the public as a restaurant and museum for Pioneer Flour Mills.