Tracking IP addresses no longer has much meaning.
The days of each internet user having a separate and distinct IP address are long gone because it is too costly for ISP's to keep buying more and more addresses to add to their systems. Now, each IP address may have many, many users on that particular address. I've had times when a friend here in my town, who has the same ISP as I do has commented on my blog, and it tells me his IP address and mine are the same.
Since some of the larger ISP's cover vast areas over state borders (using the US as an example), that complicates things even further. As an example, I can see the IP address assigned to me and my visits in the control panel for my self-hosted blog web host. At times it says I'm in Denver, CO, other times in Cheyenne, WY, sometimes in Salt Lake City, UT, and sometimes in Boise, ID. That is because my ISP covers a very large region of the western US. I don't live in any of those places, and the closest to me is nearly 400 miles away.