When Amazon introduced the Prime membership program in the United States in 2005, it gave members free two-day shipping as well as discounted one-day shipping rates for an annual fee of $79. A lot has changed since then. Amazon raised the membership fee to $99 in 2014 and added a ton of new perks for Prime members over the years. Those added benefits include free same-day delivery, unlimited video streaming, free access to a large music library, photo storage and, for the third time this year, an exclusive shopping event called "Prime Day" with tons of deals for members around the world.
Amazon’s ongoing effort to make Prime membership more attractive to customers appears to be paying off. According to estimates published by Consumer Intelligence Research Partners [PDF], the number of Prime members in the U.S. continues to grow. According to CIRP’s findings, Amazon Prime had 90 million members in the United States at the end of September 2017, up from 65 million a year earlier and around 47 million in September 2015. More importantly though, the Prime program looks to be very effective at achieving its main goal: creating loyal customers and getting them to spend a lot of money.
CIRP estimates that Prime members spend $1,300 a year on Amazon, compared to $700 for non-members. Multiply that $600 spending difference by the number of Prime members and you know why Amazon keeps adding benefits to the membership.