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# Mathematics and Primary Sources: The Evolving Postal System

The following is a guest post by Michael Apfeldorf of the Library of Congress.

Analyzing primary sources using mathematical reasoning can help students quantify historical changes over time, giving them a concrete sense of scope and scale, while providing meaningful historical perspective. This post will highlight several strategies for helping students use mathematics to better understand historical documents and events.

Consider the steady increase in the efficiency of postal services over time as a key component of the growth of the United States. Introduce this topic by asking students to examine the Schedule of Mail Deliveries from Washington, D.C. to New Orleans Mail from the Thomas Jefferson Papers at the Library of Congress. The schedule is dated 1806, just three years after the Louisiana purchase, at a time when horse drawn stage wagons carried the mail over post roads.

Students can use the information in this document  – along with average distances between cities found online or estimated using maps such as this one – to calculate an estimated rate of delivery in miles per hour.

Students working with Jefferson’s schedule may be reminded of point-to-point delivery hubs such as they might see when tracking a package they’ve ordered online. Students might study this 1802 bill to better understand that establishing these hubs – via post offices and post roads – was a critical, constitutionally mandated function of the U.S. government as the country was expanding.

Eventually, trains were routinely used to transport mail over long distances.  Once more students can determine mail delivery rates using data provided in the 1847 document To Southern Travelers!

After students have analyzed the data, ask them how much faster train delivery was compared to stagecoaches. Encourage them to explain what difference they think this made in American life at the time.

 Detail:To Southern travellers! Spring, Summer and Fall arrangement of the great southern mail line! Via Washington City, S. C. Direct to New Orleans, 1847 Detail, sheet 7: The American atlas, exhibiting the post offices, post roads, rail roads, canals, and the physical & political divisions of the United States of North America, 1839

Geometry Connections

Examining this 1839 American atlas, exhibiting the post offices, post roads, rail roads, canals, and the physical & political divisions of the United States of North America can give students additional practice looking at distance traveled from a geological – and geometric – perspective.

Begin by asking students to identify the fastest route to send a package from Washington, D.C., to Brotherton, Maryland, using the existing postal infrastructure. If they could build a new post road, how could they make this route faster?  What basic geometric principal would they use? In practice, what factors do they think planners had to consider when making decisions regarding postal routes? How might a planner combine an understanding of geometry, geography, and demographics when building the infrastructure?

Depending on the age and interests of your students, they might continue to research related topics, such as the development of telegraphy or airmail. In each case, combining mathematical and historical reasoning can help them develop their math skills further, while gaining additional historical perspectives.