1Cook bacon in 12-inch skillet over medium-high heat, stirring frequently, until brown and crisp; remove from skillet with slotted spoon and drain on paper towels. Cook onions and celery in bacon drippings 5 to 8 minutes over medium-high heat, stirring frequently, until crisp-tender. Sprinkle with salt, celery seed and pepper. Cover and refrigerate bacon.
2Layer half each of the potatoes and onion mixture in 3- to 4-quart slow cooker. Repeat layers. Pour broth over top.
3Cover and cook on Low heat setting 5 to 6 hours.
4Remove potatoes from cooker, using slotted spoon. Mix sugar, cornstarch and vinegar in small bowl; stir into liquid in cooker. Stir in bacon. Gently fold in potatoes. Increase heat setting to High. Cover and cook 20 to 30 minutes or until potatoes have thickened. Sprinkle with parsley. Potato salad will hold on Low heat setting up to 2 hours; stir occasionally.