My family has been fortunate enough to be able to host three foreign exchange students in the past. We are currently working with our local school district to see if they will take another foreign student this year as well. The agency that we are working with told me that they have 400 students that have not been placed with American families yet. If these kids don't find homes by the 31st, they won't be able to spend a year in the United States.
That is only one agency, keep in mind... there are many others as well.
Hillary Clinton urges Americans to host exchange students if they can. Please, if you have room in your heart and your home (they can share a room with a teenage child of the same sex, but they need their own bed), consider hosting a student for an academic semester or year. Our exchanges have been awesome experiences, and I highly recommend it to anyone!
YouTube - Secretary Clinton Encourages Americans to Host Exchange Students