Fundamental changes are rare and arise only in extraordinary historical situations. In order to assess the likelihood that a new voting system might be adopted it is useful to understand the circumstances under which organizations are typically motivated to change their voting systems. However, smaller changes have occurred at the national level and changes of all types have occurred below the national level and in non-governmental organizations. Many countries have made minor changes to their voting systems. In recent years the Greek voting system has undergone the most changes, with five different voting systems in use in Greece between 1974 and 1990.
Major change occurs most often at times of great social and political change.
In the United States, major changes to local voting systems are often part of a package to overhaul city government. These reforms may be proposed in response to political machines and gerrymandered districts. In the first half of the twentieth century, changes in municipal voting systems were common, due to increased awareness of the significance of the choice of voting systems. Recently, changes to U.S. municipal voting systems began occurring as a result of court enforcement of the Voting Rights Act. Often the problem is based on a popular belief that the results of a past election or the predicted results of an upcoming election are unfair or even perverse.