From the Introduction: "FY2019 is the fourth year in a row that Congress has enacted a special provision to allow for the issuance of H-2B [non-agricultural] visas beyond the annual statutory cap of 66,000 in response to high levels of demand for the visa. For FY2016, Congress exempted certain H-2B workers from the statutory cap. For the three past fiscal years, Congress has authorized the Department of Homeland Security (DHS) to make additional H-2B visas available subject to certain conditions. For FY2017 and FY2018, DHS used this authority to make an additional 15,000 H-2B visas available each year. For FY2019, DHS is making an additional 30,000 H-2B visas available."
CRS Report for Congress, R44306
Congressional Research Service: https://crsreports.congress.gov/