Delegation is a well-known feature of policymaking in separation of powers systems. Yet despite the importance of this activity, there is little systematic evidence about how many major laws in the United States actually delegate policymaking authority to administrators in federal agencies. Using a database of agency regulatory activity along with text searches, we examine significant US federal enactments from 1947 to 2016 to see which of these laws delegate to agencies. We find that nearly all major laws—more than 99 percent—contain delegation. We also find that the number of agencies receiving delegation in each law has increased over time.