John Loudon McAdam was born in 1756 in Ary, Scotland.

When his father died in 1770, young McAdam was sent to New York to live with his uncle. He worked in his uncle's counting house and managed to put away a comfortable sum before returning to Scotland in 1783. He was shocked to see the state of the roads in his home country.

He worked as a manufacturer and an auctioneer, but his mind never strayed far from the problem of fixing the nation's roads.

In 1806, McAdam became paving commissioner in Bristol and in 1827 was named general surveyor for all British highways. During his years in the paving business, McAdam came up with the idea of paving roads with layers of broken stones, all roughly the same size, placed in three layers over a convex roadbed and crushed into position by traffic.

The system came to be known as macadam or macadamized construction.

Roads were built this way for many years, but became less practical as heavy automobiles became the vehicles of choice. Cars tended to jar the stones loose. A binder for roads, made from soft coal tar, came to be known as tarmacadam.

Tarmacadam was a bit of a mouthful, so people shortened the word to tarmac.