There are currently two velodromes under construction within the United States, which, once completed will bring the total number of active US velodromes to 24. Here are some details about those new velodromes:
Rock Hill, South Carolina - Giordana Velodrome
As part of the River Walk development in Rock Hill, SC, the Giordana velodrome is currently under construction with an expected December completion date. The track will be a 250m outdoor concrete velodrome and will be part of a complex that will also include other cycling ammenities, including a BMX track, MTB trails and cycling friendly roads. The development will also have residential housing and other outdoor acvtivities.
News story on the velodrome: http://www.wcnc.com/news/local/Velodrome-Starting-to-Take-Shape-in-Rock-HIll-125763003.html
Riverwalk Development site: http://www.riverwalkcarolinas.com/cycling-outdoor-centers/veldrome/
Chicago, Illinois - Chicago Velo Campus
Currently being assembled by volunteers in South Chicago is a 166m track that will serve as a bridge to the Chicago Velo Campus groups vision of a world class indoor velodrome and cycling campus area that will accommodate various other forms of cycling. They are actively seeking volunteers over the next few weeks to help with building the velodrome, so check out their facebook page for the details:http://www.facebook.com/ChicagoVeloCampus
Chicago Velo Campus website: http://www.chicagovelocampus.com/