The article didn't really go into detail about how this works within each city. I am surprised they're scanning each city linearly, even a crude index (such as

The article didn't really go into detail about how this works within each city. I am surprised they're scanning each city linearly, even a crude index (such as boxing), or a binary search would greatly improve the lookup time. I guess if the data fits into the cpu cache the order these are scanned doesn't matter so much?