Partisan primary in the context of "Solid South"

The Progressive Era (1890s–1920s) was a period in the United States characterized by multiple social and political reform efforts. Reformers during this era, known as Progressives, sought to address issues they associated with rapid industrialization, urbanization, immigration, and political corruption, as well as the loss of competition in the market due to trusts and monopolies, and the great concentration of wealth among a very few individuals. Reformers expressed concern about slums, poverty, and labor conditions. Multiple overlapping movements pursued social, political, and economic reforms by advocating changes in governance, scientific methods, and professionalism; regulating business; protecting the natural environment; and seeking to improve urban living and working conditions.

Corrupt and undemocratic political machines and their bosses were a major target of progressive reformers. To revitalize democracy, progressives established direct primary elections, direct election of senators (rather than by state legislatures), initiatives and referendums, and women's suffrage which was promoted to advance democracy and bring the presumed moral influence of women into politics. For many progressives, prohibition of alcoholic beverages was key to eliminating corruption in politics as well as improving social conditions.

In the politics of the United States, the process of initiatives and referendums allow citizens of many U.S. states to place legislation on the ballot for a referendum or popular vote, either enacting new legislation, or voting down existing legislation. Citizens, or an organization, might start a popular initiative to gather a predetermined number of signatures to qualify the measure for the ballot. The measure is placed on the ballot for the referendum, or actual vote.

Initiatives and referendums, along with recall elections and popular primary elections, were signature reforms from the Progressive Era (1896–1917) when people sought to moderate the power of parties and political bosses. These powers are written into several state constitutions, particularly in the West. Initiatives and referendums constitute a form of direct democracy. Since 1955, states have increasingly rescinded rights to initiatives and referendums; "the strongest predictor of anti-direct-democracy proposals is Republican control of the state legislature."

First-past-the-post (FPTP)—also called choose-one, first-preference plurality (FPP), or simply plurality—is a single-winner voting rule. Voters mark one candidate as their favorite, or first-preference, and the candidate with more first-preference votes than any other candidate (a plurality) is elected, even if they do not have more than half of votes (a majority).

FPP has been used to elect part of the British House of Commons since the Middle Ages before spreading throughout the British Empire. Throughout the 20th century, many countries that previously used FPP have abandoned it in favor of other electoral systems, including the former British colonies of Australia and New Zealand. FPP is still officially used in the majority of US states for most elections. However, the combination of partisan primaries and a two-party system in these jurisdictions means that most American elections behave effectively like two-round systems, in which the first round chooses two main contenders (of which one of them goes on to receive a majority of votes).

A general election is an electoral process to choose most or all members of a governing body at the same time. They are distinct from by-elections, which fill individual seats that have become vacant between general elections. General elections typically occur at regular intervals as mandated by a country's constitution or electoral laws, and may include elections for a legislature and sometimes other positions such as a directly elected president. In many jurisdictions, general elections can coincide with other electoral events such as local, regional, or supranational elections. For example, on 25 May 2014, Belgian voters simultaneously elected their national parliament, 21 members of the European Parliament, and regional parliaments.

In the United States, "general election" has a slightly different, but related meaning: the ordinary electoral competition following the selection of candidates in the primary election.

The 1950 United States Senate election in California was held on November 7 of that year, following a campaign characterized by accusations and name-calling. Republican Representative and future President Richard Nixon defeated Democrat Representative Helen Gahagan Douglas, after Democratic incumbent Sheridan Downey withdrew during the primary election campaign. Douglas and Nixon each gave up their congressional seats to run against Downey; no other representatives were willing to risk the contest.

Both Douglas and Nixon announced their candidacies in late 1949. In March 1950, Downey withdrew from a vicious primary battle with Douglas by announcing his retirement, after which Los Angeles Daily News publisher Manchester Boddy joined the race. Boddy attacked Douglas as a leftist and was the first to compare her to New York Representative Vito Marcantonio, who was accused of being a communist. Boddy, Nixon, and Douglas each entered both party primaries, a practice known as cross-filing. In the Republican primary, Nixon was challenged only by cross-filers and fringe candidates.