The U.S. dollar bill has changed multiple times since it was first issued in 1862. Though the changes have mostly been gradual, the accumulated effect of these changes have resulted in a dollar bill that is much different today than it was during the 1860s.
Most paper currency that circulated in the late 1800s and the early 1900s were National Bank Notes, which were issued from 1863 to 1932. The federal government began printing these notes itself in 1877.
From 1933 to 1957, the closest thing to a $1 bill was a silver certificate. These silver certificates featured the treasury seal and serial numbers in red ink. In 1934, the U.S. Treasury changed the wording on the bill from "One Silver Dollar" to "One Dollar." The same year, the U.S. Treasury seal was superimposed over the "One" on the bill, and a blue "1" was added on the left side of the bill.
This blue "1" was changed to gray in 1935. The treasury seal was minimized, and stylized text of "One Dollar" was added on top of the seal.
The 1957 dollar bill was the first U.S. currency to include the phrase "In God We Trust." In 1963, the border design on the bill was redesigned, and the treasury numbers and serial numbers were first printed in green ink.