According to the spec sheet and the S4's Wiki, this model doesn't support most GSM bands for American Carriers... it does say Verizon and Sprint have a supported GSM band, however, but not their old CDMA network. HSPA+ might work, though...
But yeah, if you want full GSM compatibility (although no LTE), get the international i9500 (the i9505 LTE-enabled does NOT support American LTE).