Cruising is big business and tens of thousands of US jobs are at stake. Support staff hundreds of small US businesses depend on them.
Actually about 180,000 direct jobs. Not including preriferal jobs like restaurants, shops and hotel jobs. It's significant. And they build their ships overseas because cruise ships aren't built in the US. Probably cost issues there, along with the fact that experienced shipyards are all overseas. Not to suggest a US shipyard couldn't build one, they build military and cargo vessels for the domestic market, but the talent isn't here. And century old laws prevent the market from developing.