The following descriptive video corresponds with Figure 34 in Network Sense: Methods for Visualizing a Discipline by Derek Mueller.

What you see in the viewport is map projection centered on North America. A layer selector in the upper left-hand corner shows that all four layers are active, the basemap, which shows the land and water forms along with place names, and three layers, each of which presents with lines the synchronic or cumulative paths of 55 respondents to a survey of Canada-U.S. interdependencies in writing studies. The three layers are clustered by respondents who are early, middle, and late career based on completion year of respondents' terminal degrees.

The map displays a line for each respondent to indicate the adding up of location after location. Clicking on a line calls up the details related to the respondent's synchronic career footprint. 

Scale can be adjusted using plus and minus buttons, allowing you to zoom in on a specific region or province and to see close-up the career activity among survey respondents as relates to the designated area.