1. Both merchants and an unstable paper currency created difficulties for direct producers. 2. "In God We Trust " first appeared on paper currency since 1957. 3. Paper currency is perhaps the most common type of physical money today.4. The presidential nominee that year was U . S . paper currency . 5. Pennsylvania was one of the last colonies that emitted a paper currency . 6. American paper currency will remain valid, but coins will no longer circulate. 7. The euro is a grand experiment, a paper currency without a government. 8. The system arose in a period where paper currency was an innovation. 9. When the banks proved unable to redeem their paper currency , they collapsed. 10. In China, a national currency system existed and paper currency was invented.