It was used as a training and staging ground throughout the war. After the end of the war, it was converted into a demobilization center. In addition to camps for training soldiers, factories were needed desperately to produce ammunition to help the war effort. Four companies that produced ammunition were created during the World War I period: Atlantic Loading Co., Bethlehem Loading Company, DuPont Engineering Company, and T. A. Gillespie Loading Company. Around 1919, after the end of World War I, these companies and plants slowed and ceased production of war materials. (The Gillespie plant was destroyed by explosions on October 4, 1918.) In addition, New Jersey became a leading chemical producer worldwide after discovering German secrets. Many chemical companies in New Jersey were able to exploit their advantage to become some of the largest chemical producers. Like much of the rest of the United States, New Jersey entered a prosperous state through the 1920s. Through this period, New Jersey's population and employment rate increased greatly. Though factory production decreased after the end of World War I, production lines still remained in relatively high production. Transportation became much easier through the 1920s. Cars became easily affordable and common. Roads were paved and improved greatly. As a result, many people who had never been farther than their hometown now could travel around the state. The Jersey shore became extremely popular through this period of time. The Benjamin Franklin Bridge was completed, linking Camden, New Jersey and Philadelphia, Pennsylvania in 1926. The Holland Tunnel, under the Hudson River, was completed in 1927 providing a means of easy transportation between New Jersey and New York City. Before, ferries were required to travel across the Hudson River. Later on, the George Washington Bridge (1931) and the Lincoln Tunnel (1937) were completed, making access to Manhattan even easier. New Jersey was also the first state in the United States to ratify Prohibition, which restricted the purchasing and selling of alcohol. However, the Eighteenth Amendment to the United States Constitution, which banned alcohol manufacturing & sales, was later repealed by the Twenty-first Amendment in December 1933. Newark's breweries reopened almost immediately. Like all the rest of the United States, New Jersey was hit hard by the Great Depression. By 1933, one-tenth of the population were dependent upon the Franklin D. Roosevelt's New Deal. In fact, New Jersey issued begging licenses to the poor and unemployed people because the New Jersey government funds were growing low and were being exhausted. Under the Works Progress Administration, part of the Second New Deal by FDR, many new jobs were provided in order to support the poor and unemployed.