Although the guitar has been used from as far back as the fourth century A.D., the steel-strung guitar is a product of American popularity. Guitars with steel strings have greater volume and a "twangier" sound. Orville Gibson developed the arch-top guitar, which introduced a violin-type arched soundboard to withstand the greater downbearing of the steel strings. This instrument was particularly popular in bands and orchestras of the 1920's and 1930's. The Martin Co. of Nazareth, PA, developed the flat-top steel-strung guitar, which is slightly larger and more heavily built than the classical guitar. The flat-top has become the favorite instrument of folk and popular singers since World War II.