Four frog stamps were issued by the United States Post Office in 2019.  They include the squirrel tree frog, northern leopard frog, American green tree frog, and Pacific chorus frog (formally known as Pacific tree frog).

These amphibians have been around for millions of years.  The oldest frog fossil ever found is known as Triadobatrachus and came from the Early Triassic Peeriod.  Surviving and adapting, this species has evolved into the frogs we know today.

Frogs are known to be an "indicator species."  This means when populations of frogs are prevalent in a certain area, the environment is healthy.  Scientists believe frogs are susceptible to a poor ecosystem because they breathe through their skin.  Furthermore, they spend their adolescent life in the water and their adult life on land, giving them dual exposure.

Frogs contribute to society in many ways.  One way is by keeping the insect population under control.  Frogs are also used for scientific research and pharmaceuticals in the medical field.  From the toxins of dart frogs to the enzymes taken from northern leopard frogs, these amphibians could radically change treatments for some of the world's most life-threatening diseases.