The United States’ aviation system plays an integral role in our economy, providing a means to transport people and goods over long distances. Passenger travel within the system is growing but the system’s ability to accommodate increasing travelers may be limited. If the system is unable to offer the necessary capacity to meet passenger demand, would-be passengers may choose not to travel or choose destinations other than the United States, which could have adverse effects our economy. Addressing Future Capacity Needs in the U.S. Aviation System explores the issue of system capacity in the airspace and at select hub airports and finds that the U.S. aviation network in its current state is unlikely to provide adequate capacity to accommodate projected growth in passengers over the next 20 years. Amy Cavaretta, Paul Lewis, Joshua Schank, and Marla Westervelt, 66 pp., 2013.