Over the years NCAR has received data from over 30 different sources, including individual countries and various institutions. As such, the original data are in many different formats with varying station metadata, measurement units, and quality control procedures. To make this collection more useful it has been organized in a relational database that allows easy access in multiple ways. The station metadata have been vastly improved through careful analysis and comparison of various existing station libraries, and computed versus reported station surface elevations. The data quality has been assessed using a robust Huber regression technique and the measurement units have been homogenized. This upper-air data archive is not static, but will continue to grow with approximate monthly updates and new unique datasets as they become available. These long-term historical data are part of NCAR's Research Data Archive. Public access to the data is through a web interface (dss.ucar.edu/datasets/ds370.0/data) where users can select data by station, source, time, and geographic domain. The current output format is simple ASCII text that is sorted by station or chronologically. The access features will be illustrated and goals for future improvements will be described.