The Valco company has its roots in the National String Instrument Corporation, which was founded in 1927. The company is famous as the first manufacturer of resonator guitars, which were hugely popular in blues and (a bit later) bluegrass music. National merged with the Dobro company, another maker of resonator guitars, around 1932 to form the National Dobro Corporation. The company began producing electric instruments in the 1930s that included electric guitars, lap steels, mandolins and amplifiers. These pre-war electric instruments are fairly rare today, though the lap steels pop up with some regularity. The archtop bodies for the guitars were sourced from Regal and then from Kay, but the electronics were developed and manufactured by National-Dobro. The Supro brand name was introduced in the mid-‘30s for cheaper electric instruments.