The first Arbor Day is celebrated in Nebraska.

Arbor Day is a secular day of observance in which individuals and groups are encouraged to plant trees. Today, many countries observe such a holiday. Though usually observed in the spring, the date varies, depending on climate and suitable planting season.

Nebraska is a landlocked state in the Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwest; and Wyoming to the west. Nebraska is the 16th-largest state by land area, with just over 77,220 square miles (200,000 km²). With a population of over 2 million as of 2024, it is the 38th-most populous state and the eighth-least densely populated. Its capital is Lincoln, and its most populous city is Omaha, which is on the Missouri River. Nebraska was admitted into the United States in 1867, two years after the end of the American Civil War. The Nebraska Legislature is unlike any other American legislature in that it is unicameral, and its members are elected without any official reference to political party affiliation. Nebraska is one of only two states that divide electoral college votes by district, and is not winner-take-all.