This research introduces parallel U-shaped assembly lines with crossover points. Crossover points are connecting points between two parallel U-shaped lines making the lines interdependent. The assembly lines can be employed to manufacture a variety of products belonging to the same product family. This is achieved by utilizing the concepts of crossover points, multi-line stations, and regular stations. The binary programming formulation presented in this research can be employed for any scenario (e.g. task times, cycle times, and the number of tasks) in the configuration that includes a crossover point. The comparison of numerical problem solutions based on the proposed heuristic approach with the traditional approach highlights the possible reduction in the quantity of workers required. The conclusion from this research is that a wider variety of products can be manufactured at the same capital expense using parallel U-shaped assembly lines with crossover points, leading to a reduction in the total number of workers. / M. S. / U-shaped assembly line is a production line where material moves continuously through a series of workstations/machines arranged in a U-shape. The usage of lines is for mid-volume, mid-variety production where machines are arranged based on processing sequence. There are machines on the front and back side of U-shaped line and workers are working on the layout. Raw material entering the U-shaped assembly line, and the finished product exiting the assembly line are in close proximity to improve supervision. The advantage of the U-shaped line is that one worker can work on multiple machines at the same time promoting cross functional workers. Placing two U-shaped lines in parallel can improve workstation utilization and in turn reduce the number of workstations required. This thesis aims to provide more flexibility regarding the production of a variety of products with the same product configuration. The proposed configuration permits the manufacture of new products that belong to the same product family, while using the existing machine resources.