jackie,
I don't know if I answered your question or not, those houses were built in 1924 and 1925. Seems your block of Knox Ct is in the Highland Park Addition of Clifton and is not yet on this 1903 Map.
History of St. Louis Neighborhoods - Clifton
The earliest subdivision in the vicinity of Arsenal and Watson was Grandview Place in 1912. Several new developments occurred in that area during the 1920's, including Seever's Clifton Addition and Hampton Terrace in 1923, Highland Park in 1924 and the large Arsenal-Watson Park, between Arsenal and Fyler, in 1925. Harry C. Vollmar's subdivision was opened at Sulphur and Elizabeth Avenues in 1925 and Franke Court was developed, off of Smiley Avenue west of Tamm, in 1926. There was not further activity until the large Clifton Hills subdivision, north of Southwest Avenue and west of Tamm, was platted in 1953-55.
In 1903 there was a Blacksmith and Wagon Shop on the corner of Old Manchester Road (Southwest) and Watson. The Missouri Fire Clay Co's Clay Mine was located to the East.
Request Clifton Heights History Lookup.Title St. Louis, Missouri January 1903 #70
Description St. Louis, Missouri January 1903, Watson Rd., Old Manchester Road (Southwest), Woods, Clifton Av., Reber Pl., Marmaduke Av., Magnolia Av.
Creator Sanborn Map Company
Creation Date 1903