Today, there is currently a limit on H-2B visas that can be issued each fiscal year. A fiscal year for the Government begins from October 1 to September 30 of the following year. This annual cap is currently split for employment starting October 1 to March 30, and the other half for employment starting April 1 to September 30.
The moment the economy becomes weak, the number of requested visas does not exceed the annual limit.
On the other hand, when the economy is strong, the need for temporary seasonal foreign workers also increases, making sure that a shortage of available visas happens. It is up to the government to determine, however, if the cap has been reached. Over the years, a lot of approach and processes of raising the cap have been used.