In political science, coexistence involves different voters using different electoral systems depending on which electoral district they belong to.[1] This is distinct from other mixed electoral systems that use parallel voting (superposition) or compensatory voting. For example, the rural-urban proportional (RUP) proposal for British Columbia involved the use of a fully proportional system of list-PR or STV in urban regions, combined with MMP in rural regions.[2]
Coexistence of electoral systems exist in multiple countries, like the Democratic Republic of the Congo and Panama, as well as for elections of the European Parliament.
| Coexistence | e.g. FPTP/SMP in single-member districts, list-PR in multi-member districts | Democratic Republic of the Congo, Panama |
| Supermixed | e.g. FPTP/SMP in single-member districts, conditional party block voting in multi-member districts | Cameroon, Chad |
| Rural-urban proportional representation (RUP) | Denmark (formerly), Iceland (formerly) |