If you're curious about where Allandale stacks up compared to other Austin neighborhoods in terms of population growth, residential makeup, population density, and related figures, you will find the answers from this Excel spreadsheet made available from the Austn Neighborhood Council's web site.
The data shows that Allandale ranks 51st out of 63 in terms of percentage growth and 52nd out of 63 in terms of absolute growth. As stated in the comment below, this makes it one of the least dense, slowest growing neighborhoods in Austin.
In 2005 , Allandale had a population of 6,467, an increase of only 56 from 2000. Allandale has a total of 3,228 households most of which are single family units (2,439).