It’s hard to believe it’s been 50 years since the first Earth Day was observed on April 22, 1970.
Founded by the conservation-minded Wisconsin senator, Gaylord Nelson, Earth Day was designed to be a “national teach-in on the environment.” 
Senator Nelson wanted to tap into the same energy that was fueling anti-war activism on college campuses at that time in order to spark a grassroots movement that would bring environmental issues to the attention of his fellow politicians.
It worked.
According to earthday.org,  20 million Americans participated in demonstrations on behalf of the environment that day. Those rallies inspired the passage of the Clean Air, Clean Water and Endangered Species Acts, and led to the creation of the United States Environmental Protection Agency.
I’d intended to devote the entire column to activities that took place in Hamilton County during Earth Day, 1970, but I discovered I couldn’t remember how it was observed here and neither could anyone else I asked. 
Nancy Massey found just one related story in the April 23, 1970 Noblesville Daily Ledger concerning an Earth Day address delivered to the Noblesville Kiwanis Club.
That article noted that most local Earth Day activities were taking place in the county’s classrooms, although some students went beyond that to put up posters, collect trash or plant trees.
In fact, in later years, Hamilton County’s Earth Day events started getting lumped together with the commemoration of Arbor Day, the tree-planting holiday, because the two occurred around the same time in April and both honored the environment.
Like Earth Day, Arbor Day activities have been centered primarily around schools. When students weren’t planting trees and shrubs in their school yards and other public spaces, they presented programs designed to promote an appreciation for the beneficial role trees play in our lives.
There are differences between the two days, though.
Arbor Day is nearly 100 years older than Earth Day. Founded in Nebraska in 1872, it’s been celebrated in this area since at least 1889.
While Earth Day has always been April 22, trying to pin down the exact date of Arbor Day is a little more complicated.
National Arbor Day is celebrated on the last Friday in April (April 24 this year) and most states observe it then, but it can occur in any month since each state schedules the day to coincide with the best time to plant trees in that area. (Hawaii’s Arbor Day is in November!)
To add to the confusion, during the early years of the 20th century, Indiana had two Arbor Days, an Autumn Arbor Day in October and a Spring Arbor Day in April.
From 1898 to 1920, Indiana’s Arbor Day was known as “Arbor and Bird Day,” in an effort to also raise awareness of the need to protect our feathered friends.
And man, did they need it then. 
In the late 19th and early 20th centuries, birds were viewed as both expendable and inexhaustible. Because of that attitude, many a bird was used for target practice by young boys.
The greatest threat to birds’ existence, however, came from women’s fashion. Millions of birds were being slaughtered at that time — so many that some species were at risk of becoming extinct — just so women could wear feathers, and sometimes entire taxidermied birds, on their hats.
(Seriously. You can find photos of some of those outlandish creations on the internet.)
Indiana seems to have dropped the “Bird” portion of “Arbor and Bird Day” after 1920, but I haven’t been able to find out why. Bird Day does still exist (May 4,) though, as well as a National Bird Day (January 5.)
Thanks to Nancy Massey for additional research. 
Paula Dunn’s From Time to Thyme column appears each Wednesday in The Times. Contact her at younggardenerfriend@gmail.com