Square readers will be attached to smartphones donated by telco Sprint to Salvation Army bell ringers in San Francisco, Chicago, Dallas and New York, meaning Americans not carrying cash can still contribute.

Major George Hood, national community relations and development secretary, Salvation Army, says: "The goal of the technology behind the Square reader is simple - make transactions easier, and this year, we plan to make donating to The Salvation Army as easy as possible for our donors."

Using Square is the latest ruse from the Salvation Army to keep up with a population that is carrying less cash. According to the New York Times, three years ago, the Army tried out traditional credit card processing terminals for the Christmas Red Kettle Campaign.

However, this hauled in just $60,000 in 2009, the last year it was tried nationally, a tiny amount compared to the $148 million in coins and bills raised in 2010.

Hood told the Times: "The credit card terminals really haven't been a blockbuster, I'll be candid. The winter elements have been a negative, people have to go through a process of entering data, and it's just generally more cumbersome than we think Square will be."