Complex sentence: Until 1998, this route extended westward to Gila Bend until its replacement by Interstate 8; as such, it was known as the Gila Bend Highway and still carries that name in Casa Grande.
Split into simpler sentences: Until 1998, this route extended from its current westward terminus to Gila Bend and was known as the Gila Bend Highway. Although Interstate 8 serves as a replacement for much of its decommissioned length, the route still carries that name in Casa Grande.