I don't think an auditor would care, because again - no tax benefit, no write-offs, nothing. . . it just happens to be the other half of a duplex that we rent - meaning it causes all associated expenses, etc. to be taken at 50% instead of 100%.

I'm looking into automated skip tracing systems but for now, I use the auditor website.

@Juan Camilo Perez, I start online with the county auditor site, that lets me filter by neighborhood and property type (although I can only sort single to 4plex, then 4 -19 units and 20+ units). 

They are probably getting it from the auditors website.

My college degree is in accounting and after a couple years as an auditor I decided to jump into real estate as a broker.CCIM 101 - Financial Analysis (July 2020): Online course was taken over 2 weeks and I passed the test on August 1st.  

Let's say Tax Court (because if an IRS auditor were to disagree with me on this item, it'd make for an easy & cheap Tax Court filing) ultimately somehow says "7 year" and for some reason it actually mattered. 

How do I find land (realtor, auditor site, sheriff)2.

While they are not technically required (there is strong court precedence that taxpayers may reconstruct mileage from calendars and receipts), the IRS often disallows mileage without contemporaneous records in its entirety during audit or examination. 

I have to do a bit of digging on the auditor site to get the address, which isn't terrible.

But my plan was to look on the county auditor sites for properties that meet my criteria.