Mohsen Mosleh, Jennifer Allen, and David G. Rand

When analyzing over 10 million posts across 7 social media platforms, we find stark differences across platforms in the political lean and quality of news shared, as well as qualitatively different patterns of engagement. While lower-quality news domains are shared more on right-leaning platforms, and news from a platform’s dominant political orientation receives more engagement, we nonetheless find that a given user’s lower-quality news posts consistently attract more user engagement than their higher-quality content—even on left-leaning platforms. This pattern holds even though we account for all user-level variation in engagement, and even on platforms without complex algorithms. These findings highlight the importance of examining cross-platform variation and offer insights into political echo chambers and the spread of misinformation.