I took a look around and see what you are referring to - I've sent a message to the vendor to get some specifics.

I've received an explanation for the number of unclassified points in Nicollet county and the rest of the Minnesota River basin collect.

Data was classified into a number of different classes. The USGS Specification does not allow for the use of the standard Overlap class those points were sent back to class 1 (non ground). The overlap between flight lines was processed so there is a more equal distribution of points and the surface created from bare earth has the same density throughout the project.  This project was collected with 50% overlap so when overlap points are classified that is roughly 50 percent of each individual swath (the outer 25% from each side of the field of view) that gets classed to "overlap".  This makes for a very nice looking data set when making the bare earth surface and products.  Since an overlap class was not delivered those points were assigned to class 1 non ground because they represent all elevations of points from the raw swath.  Also, we ran a building and vegetation macro on the data as requested. The macro did a nice job  but it was not part of the contract to edit those points. When doing this the macro also put points into the class 1 non ground class. This added some more points to class 1. The main contributor is the overlap as  I mentioned above because the project was collected with so much overlap.

hope that helps explain the issue.

tim