The original pound cake, as made in colonial America, contained a pound of flour, a pound of sugar, a pound of eggs and a pound of butter (thus the name). Other ingredients might or might not be added. It's a fairly heavy cake, and variations are often used modernly by decorators when they need something sturdy for a carved cake.
My hunch would be that like many things, it came over from Britian (or elsewhere in Europe) and stayed popular here while becoming less so there, but I have no documentation for that.
Wait a minute - I have google. Ah HA!
from [
www.joyofbaking.com]:
The pound cake originated several centuries ago in England from yeast leavened bread-like cakes. The name comes from the fact that the original pound cakes contained one pound each of butter, sugar, eggs, and flour. No leaveners were used other than the air whipped into the batter. These cakes were rich and dense. By the mid 1800's pound cake recipes began to deviate slightly from the original formula to make a lighter cake. Some recipes even contained a liquid, such as alcohol or rose water. It wasn't until the 20th century that artificial leaveners (baking powder/soda) were added. Today, pound cakes use different proportions of the same ingredients as the original formula to produce a lighter cake.
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"I've often said that the difference between British and American SF TV series is that the British ones have three-dimensional characters and cardboard spaceships, while the Americans do it the other way around."
--Ross Smith