MLB’s August waiver trade period was eliminated effective with the 2019 season.
Before 2019, the July 31 deadline was commonly called the non-waiver deadline because teams could still trade players during August after those players cleared trade waivers. The system allowed clubs to make significant late-season moves, although the waiver process could block a deal or limit which teams could participate.
The rule change compressed the summer trading calendar into a single major-league trade deadline. After July 31, players could still be placed on waivers for purposes such as outright assignment, but clubs could no longer use the old waiver process to complete ordinary trades. This ended the familiar August trading period that had produced notable late-season acquisitions.
The 2019 reform is sometimes confused with later roster-rule changes or the unusual 2020 season. The pandemic-shortened 2020 campaign had its own schedule and deadline complications, but it did not change the historical effective season asked about here.