Austria

1. 1919–70. Elections by PR in 25 Wahlkreise. In 1923 the two constituencies of Tyrol are merged into a single Land constituency, and Burgenland is added. Wahlkreise can be aggregated into Länder. There are eight Länder in 1919–21 and nine since 1923 (addition of Burgenland).

2. 1971–94. Wahlkreise reduced to nine, corresponding to the Länder.

3. 1995–present. Nine Landeswahlkreise transformed into second-tier units, the first tier being 43 Regionalwahlkreise.

Belgium

1. 1847–98. There are 41 arrondissements administratifs, which can be aggregated into nine provinces.

2. 1900–91. Arrondissements administratifs are aggregated into 30 constituencies as follows: Fournes/Dixmude/Ostende; Roulers/Tielt; Tournai/Ath; Huy/Waremme; Gand/Eeklo; Tongres/Maaseik; Arlon/Marche/Bastogne; Neufchâteau/Virton; Dinant/Philippeville.

3. 1995–present. There are 20 circonscriptions (or kiesdistricte) and provinces increase to 11 given the division of the former province of Brabant into three parts: Bruxelles, Brabant flamand (Louvain), and Brabant wallon (Nivelles).

Denmark

1. 1848–1915. There are 100–13 valgkredse, which can be aggregated into 22 amter corresponding to the amtskredse and storkredse of 1918–68.

2. 1918. There are 110 valgkredse. The majority of the country still votes in single-member plurality constituencies. Voting by PR occurs only in the former 15 constituencies of Copenhagen and the three of Frederiksberg (the 18 constituencies form one PR constituency).

3. 1920–68. PR in 22 constituencies: storkredse (the 3 constituencies of Copenhagen) and amtskredse. After the September 1920 election, there are 23 units (with the addition of northern Schleswig).

4. 1971–present. There are 17 units: 3 in Copenhagen (storkredse), 7 in mainland Jutland, and 7 in the islands (amtskredse).

Finland

1. 1907–present. The overall number of electoral districts or “electoral areas” (vaalipiirit) is fixed by law between 12 and 18. Since 1907 their number has varied between 15 and 16. According to the peace treaty after World War II, Finland loses the Viipuri region (two constituencies) to the Soviet Union. Single-member constituencies with plurality elections are found in Lapland (1907–38) and in the Åland Islands (since 1948).