Nehemiah - Chapter 7
Also Known As Ezra Chapter 2
Finally, the wall was finished and the doors were installed, so Nehemiah appointed Levites as gatekeepers and singers. He placed his brother Chanani and another respected man named Chananya in charge, instructing them that the gates were not to be opened until noon, when it was hottest, in order to avoid enemy attack. At other times, the doors were to remain locked and guarded. Neighborhood watches were to be established, with everyone keeping an eye on the wall near his home.
At that time, Jerusalem was still sparsely populated, so there really weren't enough people to adequately guard the wall at all times. However, G-d gave Nehemiah an idea. (You'll notice that Nehemiah could always be relied upon to give G-d credit.) He asked the head of every family to show him their lineage records (which, as we saw in Ezra chapter 2, had generally been meticulously kept). He started with the first wave of returnees, who had come with Zerubavel. Verses 7 through 68 list the returnees, virtually parallel the list found in Ezra 2, though there are several small differences accounting for some people who went back, others who arrived later, minors who came of age, etc. Verses 69-72 reiterate the donations that were made, which can likewise be found in the account in Ezra 2.
Of course, the question is how this helped Nehemiah with Jerusalem's underpopulation problem. Ralbag and other commentators explain that Nehemiah identified the heads of the families so that he could ask each of them to send representatives to live in the capital city. (Yes, Jerusalem IS the capital of Israel!)