Just days after the last American troops withdrew from Vietnam and a day before the World Trade Center opened, Motorola engineer Martin “Marty” Cooper made the first call from a cell phone, on April 3, 1973.

“Joel, this is Marty. I’m calling you from a cell phone, a real handheld portable cell phone,” Cooper said to Joel Engel, research head at Bell Labs, who was leading Bell’s own cellular project.

The call was made from a prototype called the DynaTAC, which weighed in at a hefty 2.5 pounds (40 ounces). For perspective, Apple’s latest iPhone weighs just under one-tenth that amount (3.95 ounces).

It would take another ten years for Motorola to release the world’s first commercially available cell phone. But a costly retail price of $4,000 would prevent the technology from reaching the average consumer.

As prices dropped and portability improved, cell phone sales increased. At the turn of the millennium, over 100 million people in the U.S. had cell phone subscriptions.

The rise of smaller and affordable cell phones led to a business need for a PDA/phone device. RIM was one of the first successful developers of such devices, later coined “smartphones,” with its Blackberry line. Use of Blackberry phones nearly doubled year-to-year starting in 2003.

By 2007, however, more feature phone makers were creating smartphones. That June, Apple released its first iPhone, sparking a media blitz which caused an explosion of consumer interest in smartphones.

Since that time, smartphones have nearly pushed feature phones completely out of most major markets. Google’s open source smartphone OS, Android, powers over 500 million phones and has gained significant market share from Apple and Blackberry since its release in 2010.

In the 40 years since Marty Cooper made that first call, gloating to Joel Engel, cell phones have become a part of our daily lives and helped shape how we communicate and do business. It’s mind-boggling to think of the possibilities for the next 40 years.

What do you think the future holds for cell phones and mobile communication? Let us know in the comments below.