The U.S. Postal Service delivers mail to more than 150 million addresses using city, rural, and highway contract carriers. It also provides retail products and services in post offices in all communities. Despite the continued decline in First-Class Mail® volume, the Postal Service strives to increase its revenue while reducing operational costs in delivery and vehicle operations. The Delivery and Post Office Operations Directorate plans and directs audits and reviews that examine how the Postal Service is addressing the economy, efficiency, and effectiveness of delivery, vehicle, and retail operations.