Question

the processing centers at ellis and angel islands were gateways for millions seeking opportunity. what was a significant economic impact of this mass immigration on the u.s?
it shifted economic focus to agricultural exports.
it spurred growth in manufacturing and infrastructure.
it reduced economic output due to labor surpluses.
it limited investment in industrial technologies.

Explanation:

Mass immigration provided a large labor force. This labor force was crucial for the growth of manufacturing (as more workers could produce goods) and infrastructure (as construction and development projects needed manpower). Immigrants often took on jobs in factories, building railroads, etc., which spurred economic growth in these sectors.

Answer:

It spurred growth in manufacturing and infrastructure.