Wisconsin, a state that has long produced more cheese than any other in the US, is fighting to retain its leadership in the cheese market, according to a new report. California is quickly nearing a level of cheese production to top Wisconsin's. In the early 1990's, California overtook Wisconsin as the nation's biggest milk producer, a development that has caused Wisconsin state officials to focus on the cheese situation with severity, investing US$150m in the expansion and addition of cheese production facilities.