Peel and cut each carrot lengthwise in half, then cut diagonally into to 2-inch pieces.
In a four quart saucepan heat carrots, water, butter, 1/2 teaspoon salt to boiling over high heat. Reduce heat to low; cover and simmer from twenty to twenty-five minutes or until carrots are tender, stirring occasionally. Remove cover; increase heat to medium-high and cook until all liquid evaporates. Stir in rosemary.