As of my last knowledge update in September 2021, the longest winning streak in high school football in Miami-Dade County was held by the Northwestern High School Bulls. They had an impressive 42-game winning streak that stretched from 2006 to 2008. This streak included consecutive state championships and was one of the most notable runs in Florida high school football history at the time.

Please note that records in high school sports can change over time, so I recommend checking with more recent sources or local sports authorities for the most up-to-date information on high school football winning streaks in Miami-Dade County.