This study reports the codification of basic authority characteristics of 336 national political systems (polities) that functioned in 91 nation-states between 1800 and 1971. In form the typical 19th-century polity was an autocracy with minimal functions. Its 20th-century counterpart was either an activist plural democracy or an activist autocracy. The incidence of system-transforming political change has been equally high and pervasive in both European and Third-world polities, but greater in the 20th century than the 19th. The data are used to test three hypotheses that attribute the persistence and adaptability of political systems to their authority characteristics. “Institutionalization” arguments about the stability-enhancing effects of complexity and directiveness receive no consistent support. Conventional beliefs about the greater durability of democracies vs. autocracies vs. anocracies (uninstitutionalized polities) are confirmed only in Europe in the 20th century. The most durable historical and Afro-Asian polities have been either autocratic or anocratic. The data generally support the hypothesis that “pure” political systems—consistently democratic or consistently autocratic—are more durable than systems of mixed authority characteristics. Long-term trends in political “development” and their determinants are discussed in the light of the findings.
