The MaxRange dataset provides information on political institutions for all countries of the world going back to 1789 on a monthly and yearly basis, and to 1600 on a yearly one.  The yearly dataset spanning 1600 to 2014 has over 90,000 country-year observations, and in its monthly format from 1789 has over 660,000 observations.  The time-series data are at least 200 years longer than any other comparable time-series dataset on political institutions.  Created by Max Rånge, the datasets aggregate specific attributes to create nominal and ordinal rankings of political regimes on a 1-100 scale (the MaxRange1 dataset) and on a 1-1,000 scale (the MaxRange2 dataset).  At the same time, however, the codes for each attribute underlying the categorization of political regimes are also included.  It is more detailed than any other dataset on political institutions, yielding up to 1,000 different unique combinations of institutional features.  In addition to supporting a rigorous classification of democratic and nondemocratic regimes, the dataset allows researchers to exploit institutional variation and to explore alternative ways of aggregating political institutions.  The MaxRange dataset on political institutions is by far the biggest and most comprehensive political regime dataset to date, and it offers several advantages compared to other available data.  In particular, the availability of monthly time-series data provides greater detail and reliability to support more accurate research on political transitions.