Intra-party factions have attracted increased scholarly attention in the twenty-first century as party systems have fragmented. Yet, we lack a consistent measure to see inside the "black box" of parties, hindering our ability to study factions comparatively or understand the drivers of temporal trends. We construct an original dataset of party factionalism in candidate and leadership contests, national legislatures, and party organizations between 1990 and 2024 for all major parties across seven countries; the United States, United Kingdom, Germany, Spain, France, Canada, and Mexico. We use this combination of sources to propose a composite measure of party factionalism that can be used comparatively across time and space. Under this measure, we find that factional conflict in many of these parties steadily declined during the 1990s and early 2000s, then increased from 2007 onwards with a stark increase in intra-party factionalism in parties. Increased factionalism was primarily driven by conflict in the traditional parties of the center-right (conservatives and Christian democrats) and center-left (social democrats). Trends of growing intra-party factionalism are commonly attributed to parties "opening up" their processes with more intra-party democracy that include more diverse actors. Instead, we show that our descriptive trends are more closely connected to the entrance of new issues into the political sphere (policy) and the new affordances of digital technology that enable faction-oriented actors to foster horizontal and vertical connections (connectivity).