The City of Miami Gardens was incorporated in May 2003. Four years later, the community of 100,000 got its own police force — and not a day too soon. The area, which includes much of Carol City, is known for being one of the toughest in Miami-Dade County, with two dozen homicides in 2007 alone. (Rapper Rick Ross has chronicled the mean streets of this area in several songs). To deal with the problem, the city threw its support behind the fledgling department: It hired 159 officers from around the nation, paid them a $12,000 signing bonus, and gave them shiny new Crown Victorias. The department now has a budget of $33 million, making it the fifth largest in the county. Miami Gardens, says chief Matthew Boyd, ''is already at the bottom. The only place to go is up. And when it turns around, give us our due.... If we can get this turnaround, we will be a model for the nation.''