The set of graphs which are visible on the screen at any given time comprise all of the companies, individuals, and board memberships that existed for a single year.

 

The color of the lines reflects a comparison between the current year and the previously viewed year - namely, the previous value of the time slider at the bottom of the screen. (This previous time value might be before or after the current year chronologically.) Green lines are new connections, gray lines are connections that didn't change between the two years, and red lines (if enabled in the 'Advanced Settings' tab) are connections from the previously viewed year that no longer exist in the current year.

 

If the board member node style is set to one of the two textual options ("Last Name" or "Full Name"), the appearance of the text also reflects a comparison on each node to the previous time value. If, in the current year, an individual becomes disconnected from all of the companies he was connected to in the previously viewed year, the corresponding node "floats away" from the graphs and the text is dimmed. It is important to note that these floating nodes reflect only the individuals from the previously viewed time frame who are no longer connected to any board. If the time slider is changed again, the floating nodes that are still completely disconnected from the new graphs disappear entirely. New nodes (i.e. nodes which were not previously visible on screen), are rendered with italic text, and nodes that are unchanged between time values are rendered with plain text.

 

Clicking on a node will cause it to be locked to its current position or whatever position it is dragged to. Double clicking on a locked node will unlock it. Locked nodes can be distinguished by their emphasized outlines or bold typeface, for button and text symbology, respectively.

 

In order to increase performance, only presidents, vice presidents, and individuals who sat on more than one board from 1872 until 1894 are represented as nodes in the graphs. The total number of members of each company's board in the current year is shown as a white number in the center of the company node. The radius of each company node is proportional to the total number of board members plus a constant.

While the makeup of a single railroad's board of directors changed year to year, powerful families often moved from board to board, sat on multiple boards at once, or had multiple family members sit on the same board simultaneously. Individual names and positions may have changed each year, yet certain families maintained influence on railroad boards of directors for decades. 

 

This visualization tracks the movements of five families in Boston that all had interests in the same three railroad companies: Atchison, Topeka & Santa Fe, Atlantic & Pacific, and Mexican Central.  Certain families tended towards loyalty to one railroad while others consistently held seats on all three boards.  All five families had a family member as a founder of the American Loan and Trust Company, incorporated in Boston in 1880. 

 

Board membership did not denote control over management of a corporation as much as it meant that director's had access to inside information that was critical for investment.  In an age when public information was often partial or false, it was essential for large investors to have trusted people on boards. Important investors tended to trust friends and family members; a close network of railroad directors might form a trust company with friends and family to better act on their investment information. The emergence of bureaucratic corporations did not mean the end of insider networks based on family and kinship. 

 

Isaac Tucker Burr served as president of the National Bank of North America in Boston from 1881 for much of the 1880s and 1890. His brother, Charles Chauncey Burr, replaced him for one year on the board of Atchison, Topeka and Santa Fe.

 

Benjamin Pierce Cheney first worked as a station agent and stagecoach driver, but eventually became one of the early directors of both Wells Fargo and the firm that became American Express. Benjamin P. Cheney held the highest number of director-years from 1872 to1891. His son, Benjamin P. Cheney, Jr. appeared once on the board of Mexican Central. 

 

Thomas Nickerson left his lucrative shipping and mercantile business in 1870 to enter the railroad business. His son, Albert, and his brother, Joseph, joined Thomas on multiple boards. 

 

William Barstow Strong began his career in the railroads as a station agent in 1855, eventually rising to become president of the Atchison, Topeka and Santa Fe in 1881, a position he held until his retirement in 1889. The Atchison, Topeka and Santa Fe expanded to become 7,000 miles long during his tenure as president, making it the largest railroad in the country.

 

Levi Clifford Wade was an attorney and member of the Massachusetts House of Representatives. After 1880, Wade's law practice dealt exclusively with railway law, after which he was made official counsel for Atlantic and Pacific, Atchison, Topeka and Santa Fe, and Mexican Central.