A canal digger wrote in 1826: "We stood in mud to our knees, never told when the work would end." A historian writes crews were pushed to finish before fall shipping. What does the secondary source add?

A nurse's 1918 diary lists her ward's deaths each night. A historian compares those ward records with city burial records for the same weeks. What does the historian's account provide that the diary cannot?

A farmer wrote in 1935 that dust sifted through the window frames and settled on the supper plates. A historian's chapter explains regional plowing practices and rainfall records. What does the letter supply that the chapter omits?

A militia private wrote in 1777 that his company "won the field that morning." The historian shows the army withdrew by nightfall after fighting elsewhere. Why is the private's account limited here?

Mill workers' 1845 petition to their state legislature describes twelve-hour shifts and asks for a shorter workday. A historian cites it in a chapter on the fight for a ten-hour day. What conclusion does the historian draw from the petition?

A ship's captain logged "nine days from port" in 1849, while the historian, using harbor records, counts eleven. What does this disagreement most likely show?

An 1877 editorial blames a rail strike on "outside agitators." A historian notes that the paper's owner held rail stock. What does the secondary source add for a reader of the editorial?

A rural teacher's 1901 report says forty students shared eleven readers. A historian explains that the county bought books with property tax and the district's tax base was small. How do the two sources work together?

A miner wrote in 1902 that his pay envelope was short again. A historian describes company-store deductions written into the mine's contracts. What does the historian's explanation let a reader do with the letter?

A homesteader's 1874 letter says grasshoppers stripped her garden in a single afternoon. A historian reports crop losses across four states that summer. What does the secondary source supply?

A telegraph operator's 1861 note records messages sent "all night, none explained." A historian writes that commanders used the line to coordinate two separated columns. What does the note show that the historian's account does not?

An immigrant's 1907 letter describes waiting for hours in a crowded inspection hall. A historian gives the number processed that day and the staff on duty. Which statement best describes the relationship?

An organizer's 1913 diary calls her group's march "ours alone." A historian notes that three other groups had marched the same route that spring. What does the historian's account correct?

A bridge worker's 1871 notebook lists men who came up from the underwater caisson "bent and unable to stand." A historian explains that rapid decompression caused the illness. What does the historian add?

A railroad surveyor's 1868 field book records a route change "by order, no reason given." The historian shows a landowner filed suit that same month. What conclusion does the historian draw from the field book?

An 1841 store ledger shows most purchases marked "on account." A historian writes that cash was scarce in the county and stores carried customers until harvest. What does the ledger show on its own?

A sailor's 1813 letter says his ship "took a prize without a shot." A historian writes that the captured vessel had already surrendered to another ship that morning. What does the secondary source establish?

A student's 1933 journal says her class shrank from thirty pupils to nineteen by spring. A historian describes families leaving the county to look for work that year. What does the pairing let a reader conclude?

A resident's letter, written days after the October 1871 Chicago fire, describes dragging a trunk toward the lake. A historian explains that high wind and wooden buildings spread the fire fast. What does the letter contribute?

A lighthouse keeper's 1888 log records snow so thick that "the light showed nothing." A historian traces the storm's path up the coast across three days. Why is the keeper's log still valuable?