Michal Korach
Jerusalem’s population is particularly youthful. In 2009, the median age in the city was 24 (Half of the city’s population is younger than the median age, and half is older). By way of comparison, Tel-Aviv and Haifa are significantly older, with a median age of 34 and 38, respectively.  The national median age for 2009 was 29.
Jerusalem’s population is so exceptionally youthful because it has a relatively high percentage of children in addition to its having an unusually low percentage of seniors (age 65+).  Almost half (42%) of Jerusalem’s population is of the ages 18 and under and merely 8% are aged 65 and older. 
Of Jerusalem’s non-Ultra-Orthodox, Jewish neighborhoods, the youngest median ages per neighborhood were recorded in Har Homa (21), Givat Mordechai (23) and French Hill (26).  Conversely, the highest neighborhood median ages were recorded in Kiryat Wolfson (68), Nayot, Neve Geranot and Neve Sha’anan (47) and Talbiye (45).  
Among Jerusalem’s Ultra-Orthodox neighborhoods, the lowest neighborhood median ages were recorded in Kiryat Keminitz in Neve Yaakov (15), Ramat Shlomo (16), Me’a Shearim and Batei Ungerin (16).  The highest neighborhood median ages were found in Kenesset and Batei Broida (31), Sha’arei Hesed (25), Har Nof and Bayit VeGan (20). 
A similar study of Arab neighborhoods could not be performed for lack of available data. 
The graph below shows that non-Ultra-Orthodox localities surrounding Jerusalem had a higher median age than in Jerusalem, while localities surrounding Jerusalem with large Ultra-Orthodox populations had a lower median age than in Jerusalem.