This paper uses newly released data on political behavior (V-Dem) and urban growth (the Atlas of Urban Expansion) to identify, for the first time, a statistical correlation between clientelism (the informal provision of benefits, including urban land and services, to the poor in contingent exchange for political support) and informal urban growth, across a globally representative sample of 200 cities. The paper finds that, consistent with theoretical expectations, cities in more clientelistic countries are likelier to experience urban growth in the form of informal settlements that appear to have been planned in advance of settlement (‘informal subdivisions’), but are not necessarily likelier to experience unplanned, ad-hoc informal growth. The main model for informal subdivisions finds that if a country were less clientelistic by one point on a 0-10 scale in 1990, the proportion of residential growth in the form of informal subdivisions between 1990 and 2015 in its cities would decrease by 16% of its previous value, a magnitude equivalent to that of an increase in 1990 GDP per capita of $2,700. These results support the notion that informality is not simply associated with poverty but also with politics. They indicate that particular political dynamics may have a spatial ‘signature’ on the urban landscape; that, conversely, certain urban spatial forms may generate certain kinds of politics; or both. The paper provides an example of how newly available data may be used to advance our understanding of the relationship between politics, urban space, and informality.