In the short run, the Pendleton Act did not have a tremendous impact on the United States. Over time, however, that impact has grown and it is fair to say that the law has transformed the way our government works.
When it was first enacted, the Pendleton Act did not have much effect because it applied to so few people. The law only applied to about 10% of all federal employees. It did not apply at all to employees of state and local governments. This ensured that its impact would be limited.
Over the years, however, the law came to cover more and more employees of the federal government. Today, it covers roughly 90% of federal employees. As the federal government expanded, it started to apply the Pendleton Act to states and localities when it gave grant money to those lower levels of government. The Pendleton Act helped to bring about the situation that we now have in which we can expect our government bureaucrats to be selected on merit and to be largely free from political bias. This is a significant effect.