JOBE,
You never mentioned "plot maps" that I recall. However, I think you're trying to say PLAT MAPS -- the drawings used to record property boundaries and legal descriptions. Incidently, a LEGAL DESCRIPTION is always included in the description of a property because a VERBAL description often better describes boundaries than a drawing for obvious reasons.
For example, your 1st aerial photo-map is very grainy. Placing the blue lines on the map where you THOUGHT the USGS marker was is an APPROXIMATION -- not exact. You may be off by several yards. In fact, your blue lines themselves are fairly wide representing an area perhaps 10 or 20 feet wide or more in terms of the scale of that photo. Being off by a single pixel in the photo could throw your line off by a substantial distance. The width of your blue line itself is as wide as a river.
On the other hand, the LEGAL description may go something like this: The Bowen Ranch consists of: "The west half of the northeast quarter of Section 11, Range X, Township X." Or, it may read something like this: "From a point at the USGS marker at the center of Section 11, Range & Township X, extending approximately 1/2 mile north to a point intersecting Bowen Ranch Road, east approximately 1200 feet to a landmark (tree, river, rock outcropping, etc), south to a point intersecting something else; west to the USGS marker."
From this data one could then accurately determine property lines. YOUR problem then consists of determining precisely where Section 11 is, but short of using GPS and/or at least one legal landmark, I don't see how you're going to accurately determine this.
And how is it that you're now an expert on property boundaries when you don't even know where NORTH is? Back to Boy Scouts Astronomy Merit Badge 101 for you, kiddo.