To provide quality services and reduce operating costs, it is important for transit agencies to know the transit passenger origin and destination (OD) demand. Such demand often changes over time and season and is critical for optimizing transit schedules and improving transit network design. It is also useful for adjusting transit service plans in response to emergency situations such as the Marathon Bombing or planned events such as baseball games. Existing automated passenger counting (APC) systems only count the numbers of boarding and alighting passengers at each bus stop or train station. With this data, it is difficult to derive accurate passenger OD information. Given that 91% of American adults now own a cell phone and 56% of them own a smartphone, this proposed research aims at accurately estimating public transit passenger OD data using cell phones as probes. The proposed method is based on Bluetooth and Wi-Fi technologies and will be tested using a bus line in Lowell, Massachusetts. The true passenger OD data will be collected to verify the accuracy and feasibility of the proposed method. In addition to OD data, this proposed method is expected to provide other detailed and useful information such as passenger waiting time..