There was an understandable plummet of interest in public-private partnerships during the Great Recession - governments were just trying to keep daily operations funded. That's created a backlog of deferred maintenance as well as new infrastructure projects for many state and local governments.
P3s are becoming more popular as vehicles to fund those projects. There's a good list in this article of some of the more recent ones focusing on roads and transportation projects.
Washington and many state governments have come around in seeing the P3 model as a not only convenient means of financing, but also in many cases, the only option. There is no official tally of P3 projects underway in the United States, but it is growing into the preferred method of financing highway improvements and other daunting infrastructure projects.