The explanation is that in March 2020, sawmills shut down and ceased production, reducing supply, while demand increased. There is evidence that there is no lumber shortage, but that the market is being manipulated by third party lumber buyers who are storing it and withholding it from the market. When only a few companies control the market, they can create a false scarcity. Government was the ultimate market manipulator when it imposed lockdowns that kept people at home and allowed big chain stores to remain open. Money and power concentrated into the big box stores while small business were crushed.