Electoral context

After the dissolution of the union with Sweden (1905), elections to the Norwegian Parliament (Storting) were decided by a two-round runoff system. In the first round, a candidate was elected if he received an absolute majority of votes cast in the district. If no candidate received an absolute majority in the first round, a second round was held within a few weeks. In the second round, candidates could enter even if they had not run in the first round.

The first formal political parties were established two decades before the dissolution with Sweden: the Liberals (Venstre) and Conservatives (Høyre) in 1884, and the Labor Party (Arbeiderpartiet) in 1887. However, up until the 1909 election, the party system was in a state of flux (Helland and Saglie Reference Helland and Saglie2003). From the 1909 election onwards, three party ‘blocs’ dominated: the Labor Party; the Liberals and Labor Democrats (Arbeiderdemokratene; est. 1906); and the Conservatives and Progressive Liberals (Frisinnede Venstre; est. 1909). Various other minor parties and organizations also fielded candidates in the runoff period, including the Norwegian Agrarian Association (Norsk Landmandsforbund; later Norges Bondelag; est. 1896).

In the first decades of the twentieth century, the Storting agenda was dominated by discussions concerning the primary industry, military budgets, educational reforms and infrastructure expansions (especially by rail) (Høyland and Søyland Reference Høyland and Søyland2019). Class antagonisms were acute in this period and the labor movement was hostile to bourgeois society (Helland and Saglie Reference Helland and Saglie2003).

With the expansion of the franchise, support for the Labor Party substantially increased. Appendix Figure A.1 shows the vote shares and seat shares for the three dominant and a residual ‘other’ category over the 1909–1927 period. The two-round runoff system led to a systematic under-representation of the Labor Party. This sitatuation mostly benefitted the Liberals, who formed a single-party government from 1913 to 1920.

The Liberal Party mainly represented rural interests against the interests of the urban Conservative establishment. The Liberals were also social reformers, though, introducing early welfare state reforms when in government, which extended their appeal to lower-income rural voters after universal suffrage. Nonetheless, the Liberals shared strategic interests with the Conservatives, in a common ‘bourgeois bloc’ against the growing support for Labor among the industrial working class (Valen and Rokkan Reference Valen, Rokkan and Rose1974).

In July 1917, parliament appointed a commission to consider changes in the electoral system. This commission presented its reform proposals in April 1919. Finally, in November 1919, MPs voted on five alternative reform proposals. A system of closed-list PR in MMDs obtained the necessary two-thirds majority (Cox, Fiva and Smith Reference Cox, Fiva and Smith2019). The new electoral system, effective from the 1921 election, grouped old SMDs into twenty-nine MMDs with a magnitude of 3–8 seats. The total number of seats in the Storting increased from 126 to 150. The seat allocation method chosen was the D'Hondt formula, which tends to favor larger parties in smaller-magnitude districts.

The conventional wisdom holds that the adoption of PR in many European democracies in the early 1900s came about as a strategic effort by bourgeois parties to preserve political power (Boix Reference Boix1999; Rokkan Reference Rokkan1970).Footnote ¹ However, there are many cases in which PR reforms ‘did not help old elites to maximize their seat shares’ (Calvo Reference Calvo2009, 256). In the case of Norway, the Liberals dominated in parliament under the runoff system, but received only about a quarter of the seats after the adoption of PR. Rodden (Reference Rodden2009b, 2) points out that the Rokkan-Boix argument ‘has always had an uncomfortable relationship with certain facts. Above all, as a bulwark against the left, proportional representation can only be viewed as a colossal failure’.

Leemann and Mares (Reference Leemann and Mares2014) provide a reformulation of the Rokkan-Boix theory: they argue that PR is introduced when legislators face strong district-level competition and when their parties expect to gain seats from a change of the electoral law. Using data from Germany, they find support for this revised hypothesis. In the case of Norway, Cox, Fiva and Smith (Reference Cox, Fiva and Smith2019) similarly find that the district-level electoral threat facing individual legislators explains roll-call votes concerning PR adoption. They also emphasize how PR affected party leaders' control over nominations, thereby enabling them to discipline their followers and build more cohesive parties, and find empirically that party leaders were more likely to vote in favor of PR adoption than rank-and-file members.Footnote ²

After the introduction of PR, the Norwegian Agrarian Association decided to form the Farmers Party (Bondepartiet; later Senterpartiet) at the June 1920 national congress of the association – only six months after the electoral reform bill had passed through parliament.Footnote ³ In 1918, the association fielded candidates in approximately 20 per cent of the single-member districts and won three seats.Footnote ⁴ In the 1921 election, after the introduction of PR and the formal establishment of the Farmers Party, they presented lists of candidates in about 80 per cent of the multi-member districts and won seventeen seats.

There was also a change within the Labor bloc. Following the 1917 Russian Revolution and the establishment of the Communist International in 1919, the Labor bloc in Norway split between supporters of communist revolution and supporters of a parliamentary road to socialism. Initially, the Norwegian Labor Party (DNA) joined the Communist International, which led to the formation of the Social Democratic Labor Party (NSA) in 1921, as a breakaway on the right of the party.Footnote ⁵ These changes within the Labor bloc were driven more by external events than electoral reform in Norway. Nonetheless, without the electoral reform, it is unlikely that the NSA and DNA would have both stood candidates throughout the country.

Political fragmentation before and after reform

Following Cox, Fiva and Smith (Reference Cox, Fiva and Smith2016), we construct a balanced panel data set of ninety-one ‘SMDs’ covering the elections between 1909 and 1927, with a total of 637 observations.Footnote ⁶ Based on this data, Appendix Figure A.2 documents a step-change increase in the effective number of parties (ENoP) following the electoral reform, suggesting that the fragmentation of the party system was immediate in Norway in the 1921 election.

In Appendix Table A.2 we analyze how the ENoP changed with the introduction of PR when adding (district-level) controls for the Farmers Party, the Social Democratic Labor Party and the Communist Party. The lack of any clear relationship between PR and ENoP when flexibly controlling for party entry via fixed effects (Column 5 in Appendix Table A.2) suggests that voters were unresponsive to the new electoral rules. Yet, we consider the estimates reported in Appendix Table A.2 to be lower bounds on the extent to which PR affected voter behavior. These are lower bounds because not only do parties act strategically to decide whether to form overall, they also target their resources strategically by deciding to stand in districts where they have the highest opportunity of winning seats. We therefore proceed with a sharper empirical test in the next section.

Strategic coordination between existing blocs

To isolate strategic switching between existing parties we restrict the panel data set to ‘SMDs’ in which the three dominant blocs participated in all election years; forty-two out of ninety-one SMDs fulfill this criterion.Footnote ⁷ This essentially limits the sample to SMDs in which all party blocs ran every year before the reform.Footnote ⁸ Restricting the sample in this way allows us to isolate shifts in the distribution of votes between these party blocs, while holding the number of blocs participating constant.

In this analysis, we are interested in how the electoral system reform affected the relative vote shares of the three main party blocs. For example, if voters coordinated between the Liberals and Conservatives before the reform, we should expect Liberal votes to go down in places where they were stronger than the Conservatives and up where they were weaker than the Conservatives. To identify these effects we define the pre-reform advantage of party i over party j to be (VS ⁱ − VS ^j)/(VS ⁱ + VS ^j), where VS denotes party vote shares. Because of what we know about the political positions of the three main party blocs – where the Conservatives are on the right, Labor are on the left, and the Liberals are between the other two blocs but much closer to the Conservatives – we expect the electoral system reform to have a bigger effect on vote trading between the Liberal and Conservative blocs than between the Liberal and Labor blocs, and limited vote trading between the Labor and Conservative blocs.

As discussed, the ‘bourgeois’ parties (the Conservatives and Liberals) shared common interests against the rising electoral support for Labor. Before PR, these two blocs had incentives to coordinate to defeat Labor candidates. As a result, in districts where the Liberals were not competitive, Liberal voters should strategically have supported Conservatives, and vice versa. The introduction of PR, which lowered the electoral thresholds, reduced these coordination incentives. As a result, Liberal voters who had previously voted Conservative could now support the Liberals, while Conservative voters who had previously supported the Liberals could now support the Conservatives, without these choices affecting the overall electoral fortunes of these two parties relative to Labor.

This is exactly what Specifications 1 and 3 from Table 1 show. We illustrate this key result in Panels 1 and 3 of Figure 1. Overall, the vote share of the Liberals fell between 1918 and 1921, as some of their voters switched to the Farmers Party, which had decided to stand candidates in most districts. The Farmers and the Liberal Party were now both competing for rural interests. However, in districts where the Conservatives were well ahead of the Liberals in 1918, such as in District A, the Liberal vote rose in 1921 (relative to the average), while in districts where the Liberals were well ahead of Conservatives in 1918, such as in District B, the Liberal vote fell in 1921.Footnote ⁹

Figure 1.

Vote-trading between blocs between 1918 and 1921

Note: the scatterplots and fitted lines correspond to Specifications 1, 2, 3 and 4 of Table 1. The y-axes measure the percentage point change in vote share for the four different blocs between 1918 and 1921. The x-axes measure the Liberal advantage over the Conservatives in 1918. In the pre-reform period we use first-round vote shares. The sample is restricted to SMDs in which the three dominating blocs are participating in all election years. Shaded areas represent 95 per cent confidence intervals based on robust standard errors. We highlight two example districts: Nordland city district (District A) and Nordland county 2nd district (District B).

Table 1.

Vote-trading between blocs between 1918 and 1921

Note: the dependent variables are percentage-point change in the vote share from 1918 to 1921 for the bloc given in the header. The sample is restricted to SMDs in which the three dominating blocs are participating in all election years (n = 42). In the pre-reform period we use first-round vote shares. Heteroscedasticity-robust standard errors in parentheses. Cluster-robust standard errors based on the post-reform district level in brackets (eighteen clusters).

Column 1 of Table 1 shows that 52 per cent of the variation in ΔVS ^LIB is explained by variation in the pre-reform Liberal advantage. A one-standard-deviation increase in the pre-reform Liberal advantage over the Conservatives (0.51) is associated with an eight-percentage-point reduction in the Liberal vote share. Such a fall in the Liberal vote share appears to have benefited the Conservatives and the Farmers Party in about equal proportions (Columns 3 and 4), while leaving Labor vote shares roughly unaltered (Column 2).

In Columns 5–8 of Table 1 we analyze how the Liberal advantage over Labor correlates with vote share changes pre- and post-reform. Again, we see that a large Liberal advantage is associated with a fall in the Liberal vote share, but it seems that these votes were captured by the newly established Farmers Party, and not the Labor bloc.

In Columns 9–12 of Table 1 we analyze how the Labor advantage over Conservatives correlates with vote share changes pre- and post-reform. Here, the results shows that Labor tended to lose votes the stronger their (pre-reform) advantage over the Conservatives was (Column 10), while the opposite is true for the Conservatives (Column 11). Puzzlingly, we find that the Liberals tended to lose out when Labor had an advantage over the Conservatives (Column 9). This unexpected correlation may be driven by the fact that in districts where Labor had an advantage over the Conservatives, then typically a similar advantage existed for the Liberals over the Conservatives.

Strategic entry cannot drive our findings in Table 1 since our sample is restricted to cases where the relevant blocs participated in all election years. What about other elite-level explanations? For example, one could imagine that after the introduction of PR, parties might start to nominate better candidates in districts in which they were previously uncompetitive, and this might be driving voters’ decisions to switch parties (see also Becher Reference Becher2016).Footnote ¹⁰ To address this concern, we use candidate-level occupation data from the Fiva and Smith (Reference Fiva and Smith2017) dataset. Appendix Figure A.6 shows how the share of white-collar workers, blue-collar workers, farmers and a residual other category evolved over the 1909–1927 period by party bloc. For the Labor bloc, there is some indication that the introduction of PR led to an increase in the share of blue-collar candidates. For the Liberal and Conservative blocs the share of candidates from the four occupational groups are stable over the sample period. Still, this could mask across-district heterogeneity in the composition of candidates that potentially changes with the PR reform. We therefore include a set of controls at the district-bloc level to our regression framework. Appendix Table A.3 provides the results. Even though the R ² increases substantially in some specifications, the coefficients of interest do not change much, suggesting that elite-level adjustments are not driving the findings in Table 1.Footnote ¹¹

As a placebo test, we look at vote share changes as a function of the (lagged) Liberal advantage over Conservatives in non-reform years. Figure 2 shows these results (Panel A, B, C, E and F) along with the actual reform analysis (Panel D). We observe that the reform year stands out when compared to the non-reform years. In non-reform years there is no clear systematic pattern between the (lagged) Liberal advantage over Conservatives and the vote shares of these blocs.Footnote ¹²

Figure 2.

Vote-trading in reform and non-reform years

Note: the scatterplots and fitted lines correspond to Specifications 1, 2, 3 and 4 of Table 1. The y-axes measure the percentage point change in vote share from year t – 3 to year t for the bloc given in the title of the sub-panel. The x-axes measure the Liberal advantage over the Conservatives in year t – 3. In the pre-reform period we use first-round vote shares. The sample is restricted to SMDs in which the three dominating blocs are participating in all election years. Shaded areas represent 95 per cent confidence intervals based on robust standard errors.