Central Park was difficult to construct because of the generally rocky and swampy landscape.[5] Around five million cubic feet (140,000 m3) of soil and rocks had to be transported out of the park, and more gunpowder was used to clear the area than was used at the Battle of Gettysburg during the American Civil War.[6] More than 18,500 cubic yards (14,100 m3) of topsoil were transported from Long Island and New Jersey, because the original soil was neither fertile nor sufficiently substantial to sustain the flora specified in the Greensward Plan.[5][6] Modern steam-powered equipment and custom tree-moving machines augmented the work of unskilled laborers.[6] In total, over 20,000 individuals helped construct Central Park.[6] Because of extreme precautions taken to minimize collateral damage, five laborers died during the project, at a time when fatality rates were generally much higher.[99]