David Clark was born in Ireland and came to America when he was only eight years old. His family was poor, and after only one year of grade school the boy left to find work.

His first job was selling newspapers and carrying market baskets. Then, at the ripe old age of 12, he attended business college, taking courses at night after working during the day.

His first job as an adult was in a frame factory where he earned $1.50 a week. After that, he moved from one job to another, working at everything from paint manufacturing to selling fish. Finally he found steady work with a small New York candy manufacturer. He drove the delivery wagon, peddling chocolates door to door.

After three years in the job he had enough money to buy the wagon, horses, and merchandise, and in 1886 he went into business for himself. He manufactured his candy in a small house in Allegheny, Pennsylvania, and sold it from the wagon. The success of his chocolate business surprised even Clark.

During his life, the D. L. Clark Company became a leading manufacturer of confections, and the Clark Bar, introduced during World War I, made Clark a household word.