The California aqueduct system has a total length of 444 miles and the main branch is 300 miles [1]. More important is the demographic impact of water management: Rome's largest population center was ~1 million people, the Hohokam ~80,000 as compared to the Los Angeles metro's 18 million. Preindustrial populations had very little capacity to built large infrastructure projects like these. Huge population centers consuming substantially more water than is brought to them naturally is a very recent phenomenon, Roman aqueducts and Hohokam irrigation notwithstanding. In most years Los Angeles imports 80-90% of its water. Situations like these are not possible without industrialized water infrastructure. Los Angeles used to be primarily supplied by the Los Angeles river and its population was correspondingly lower.

Human need water daily to survive, and without pumped plumbing building a population center that isn't near a lake, river, or with access to groundwater is effectively impossible. The Hohokam were no exception. Their aqueduct system did not exist to deliver water to the city center, but to their agricultural settlements. Their main population center was along the Gila river. Preindustrial irrigation systems are impressive when considering they were built without machines, and moreso in hostile terrain like the Sonoran desert or Afghanistan [2] - but it pales in comparison to the demographic impact of water management systems built over the last century.

1. https://en.wikipedia.org/wiki/California_Aqueduct

2. https://en.wikipedia.org/wiki/Qanat