state highway 45 south from the northern junction with us 183 to the southern junction with i-35 in travis county. in the united states this stage is known as middle school. about 29% of residents were under the age of 18; 10.4% were between the ages of 18 and 24; 24.8% were from 25 to 44; 19.7% were from 45 to 64; and 16.4% were 65 years of age or older. 