Any road closures which you know of at least 2 days before the closure is supposed to end, should be reported using the Road Closure Form linked to on the Road Closure page above. This form can also be reached by going to http://j.mp/WazeClosure
See New York/Closures for a list of (recurring) events and closures in New York, and to coordinate with other editors in the region on submitting these events and closures to Waze.
The Federal Highway Administration keeps a website indexing all states that can provide highway and construction project information. Go to the page, find your state, and check the links for the desired information.
New York City has a list of closures at the GIS for NYC. You can also access weekly, and weekend construction reports published by the NYC DOT.
Some other counties have GIS systems that may provide useful information as well.