Peel and cube potatoes. Combine water, potatoes, celery and carrot in medium saucepan. Bring to a boil over high heat. Reduce the heat to medium; simmer until vegetables are tender, about 10 minutes.
2
Meanwhile, melt butter in a large saucepan over medium heat. Add green onions; cook and stir onions in butter until tender but not browned, about 2 minutes. Stir in flour and salt. Cook and stir for 1 minute.
3
Stir milk and potato mixture into flour mixture; cook and stir over medium heat until bubbly. Cook and stir 1 minute more. Stir in American cheese, Swiss and caraway seeds. Reduce heat to low; simmer unitl cheeses are melted and the mixture is hot, stirring constantly.
