Small World Networks
Compare the two pictures below. These graphs certainly look very different. In the problem set you will be asked to compare them, using as many properties as you can, learned on the page Properties of Graphs.
The first picture represents the routes in the continental USA for one particular airline.
The second picture shows the major highways in the continental USA. In this picture there is a vertex at every intersection of edges, even if it is not marked as such or named as a large city.