“After they had cleared part of this [land]slide away, the old hill politely slid back again, completely filling the canal.”
— American engineer, about 1906

Once yellow fever and malaria were brought under control, the United States began construction in earnest. Heavy machinery and thousands of workers from nearly 50 countries spread out across the isthmus in military precision.

Conditions along the route varied considerably, from swamps and grassy plains on the coasts to rocky mountains in between. Digging equipment met with little resistance in coastal areas, but labored in the mountains, which comprised some of the most difficult and unstable terrain engineers had ever encountered.

Workers used air-driven rock drills to bore holes for dynamite charges. After the blasts, rail-mounted steam shovels scooped up the spoil and dumped it onto nearby railroad cars.

Graders and spreaders did the work of hundreds of men with shovels. They moved spoil dumped from railroad cars away from the tracks to make room for the next load.

The high quality of American heavy machinery was critical to U.S. success in Panama. Engineers easily adapted drilling, digging, moving, unloading, spreading, and grading equipment that had been originally developed for the railroad industry. The Isthmian Canal Commission’s catalog of its heavy equipment includes more than 4,000 flatcars, 200 locomotives, and 100 steam shovels.

No part of the canal was more visually dramatic than Culebra Cut, the nine-mile-long (14.5-km) excavation through a gap in Panama’s continental divide. Repeated earth slides, usually after heavy rains, plagued the work, burying equipment and destroying months of progress. Floating dredges, like those seen here in the foreground, removed the mud and rock of the Cucaracha slide, one of the cut’s largest and most destructive. An assistant engineer aptly described Cucaracha as “a tropical glacier — of mud instead of ice.”

French equipment was often too light or ill-suited for the rugged inland terrain. When the Americans arrived in 1904, abandoned railroad and excavating equipment littered the jungles. These nameplates were removed from some of that machinery.

Most of the American workers who came to Panama were skilled workers and were paid in gold. The majority of the work force were unskilled laborers, who earned less and were paid in silver.

Roosevelt “teddy” bears tackled their digging with the jingle: “To finish this great work / We need no foreign aid, / For we can do it all ourselves / With spirit and with spade.”

These cards gave the folks at home a glimpse of Panama.

In November 1906, President Theodore Roosevelt made a three-day visit to Panama to see the canal and the conditions under which the Americans labored and lived. Wishing to experience the climate at its worst, the president specifically chose the rainy season for his visit, later writing that he “tramped everywhere through the mud.” In this famous photograph, Roosevelt sits at the controls of a 95-ton (86-metric-ton) Bucyrus steam shovel at the Pedro Miguel locks.