Daniel Craig McCallum was a railroad engineer

Railroad engineer

A railroad engineer, locomotive engineer, train operator, train driver or engine driver is a person who drives a train on a railroad...

 and manager

Management

Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...

.

McCallum was born in Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 in 1815. In 1822 his family emigrated to New York

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 when he was still a boy. In Rochester he spend a few years at elementary school, and didn't follow his fathers footsteps to become a tailor

Tailor

A tailor is a person who makes, repairs, or alters clothing professionally, especially suits and men's clothing.Although the term dates to the thirteenth century, tailor took on its modern sense in the late eighteenth century, and now refers to makers of men's and women's suits, coats, trousers,...

. Instead he left school to become an accomplished carpenter

Carpenter

A carpenter is a skilled craftsperson who works with timber to construct, install and maintain buildings, furniture, and other objects. The work, known as carpentry, may involve manual labor and work outdoors....

 and did some designing as an architect

Architect

An architect is a person trained in the planning, design and oversight of the construction of buildings. To practice architecture means to offer or render services in connection with the design and construction of a building, or group of buildings and the space within the site surrounding the...

.

He became the General Superintendent of the New York and Erie Railroad in 1855, then founded the McCallum Bridge Company in 1858. He was an early proponent of the organizational chart

Organizational chart

An organizational chart is a diagram that shows the structure of an organization and the relationships and relative ranks of its parts and positions/jobs...

 as a way to manage business operations.

In February 1862, Edwin M. Stanton

Edwin M. Stanton

Edwin McMasters Stanton was an American lawyer and politician who served as Secretary of War under the Lincoln Administration during the American Civil War from 1862–1865...

, the Secretary of War

United States Secretary of War

The Secretary of War was a member of the United States President's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War," was appointed to serve the Congress of the Confederation under the Articles of Confederation...

, appointed McCallum Military Director and Superintendent of the Union railroads. McCallum's successful organization and management of the railroads earned him a promotion to Major-General.

McCallum developed the McCallum inflexible arched truss, used in wooden railroad bridges across the US and Canada in the 19th century. The advent of steel bridges effectively made obsolete his unique design. The only remaining example in the world of the McCallum truss is the Percy Covered Bridge (1861)

Powerscourt Covered Bridge

The Powerscourt Covered Bridge, alternately known as the "Percy Covered Bridge" spans the Chateauguay River, between the municipalities of Elgin and Hinchinbrooke, in SouthWest Quebec.- Overview :...

, ironically an automobile and footbridge

Footbridge

A footbridge or pedestrian bridge is a bridge designed for pedestrians and in some cases cyclists, animal traffic and horse riders, rather than vehicular traffic. Footbridges complement the landscape and can be used decoratively to visually link two distinct areas or to signal a transaction...

. It crosses the Chateauguay River

Chateauguay River

The Chateauguay River has its source in northern New York State in the United States. It winds its way through several towns and villages in Quebec, Canada, such as Huntingdon, Dewittville, Ormstown and Châteauguay before emptying into the Saint Lawrence River near Montreal.The river is home to...

 at Powerscourt, Québec, between the municipalities of Elgin

Elgin, Quebec

-About Elgin:Elgin is a rural municipality of less than 500 people in Quebec, Canada. The population as of the Canada 2006 Census was 458. It is located southwest of Huntingdon and bounded by the Trout and Chateauguay rivers and the Québec - US border...

 and Hinchinbrooke.

He also wrote a set of poems, the most famous of these was called 'Lights on the Bridge', which he wrote shortly before his death for his friend, Sam Campbell, who was a fellow railroad engineer, but was killed in 1842.