Since taxes are assessed annually, you can use these records to trace valuation increases and decreases over periods of time. A large jump in valuation from one year to the next could indicate new construction or an addition to the property. You may also find personal property tax rolls very helpful as they usually inventory some kinds of personal possessions. These records are usually organized by township or city and by legal description. You can access these tax records by visiting the county clerk or county treasurer.  And, usually are also kept at a state archives.