If you still haven't joined Amazon (NASDAQ:AMZN) Prime, you're in a rapidly shrinking group of Americans. Amazon doesn't release Prime subscriber figures, but according to Consumer Intelligence Research Partners, Prime memberships in the U.S. had burgeoned to 85 million by July, up 35% from the year before. That figure may be high: An analyst with Wedbush Securities pegged Prime's U.S. subscriber total at 52.5 million. Assuming the right number is in the middle of those estimates, that means over half of Americans already have access to Prime, given that there are 126 million households in the U.S.

With the holiday shopping season right around the corner, many of those holdouts may be considering finally joining Prime. After all, online shopping as a percentage of total retail sales spikes during the holiday season, as Americans look to get all their gifts on time, avoid the crush of stores and malls, and stay out of the cold winter weather.

"Black Friday" written in black balloons

Image source: Getty Images.

Amazon wants you

Amazon knows that promotional holidays and gift savings opportunities are great ways to entice new customers to join Prime. It's already invented its own shopping holiday for its loyalty members, Prime Day, the midsummer bash that is now the company's biggest sales day of the year; Black Friday presents a similar opportunity.

Amazon is currently advertising items like strollers, smart speakers, hoverboards, and board games under Black Friday Deals Week on its website. It has also taken the aggressive step of discounting some popular third-party items, essentially subsidizing the discounts by paying merchants the difference.

That would seem to make holiday shopping on Amazon even more appealing, as the e-commerce giant is making a particular effort to offer the lowest prices on such items. However, shoppers should be mindful that Amazon doesn't always have the lowest prices. In fact, the company's strategy is to set prices most competitively on the most popular items, in order to burnish its reputation as the low-cost provider, but it tends to charge more on less popular products.

Should you join Prime for Black Friday?

The best reason to join Amazon Prime for the holidays, then, isn't price but convenience. If you're searching for a lot of obscure items, Amazon gives you the greatest chance of finding them all in one place, and Prime means you can get free shipping on even the smallest orders, so you don't have to pay for your shopping all at once.

Even better, you can join Prime for free with a 30-day trial, or pay just $10.99 each month if you've already had a free trial and you don't want to commit to the standard $99-per-year payment. Such an option makes it easy to use Prime just for holiday shopping. This may make Prime a better option than Costco for holiday shoppers willing to join a membership service, as Costco requires you to shell out $60 up front for an annual membership.

If you're still on the fence about joining Prime for the holidays, you may want to download a price-comparison app so you can see if Amazon offers the best prices on the gifts you want to purchase. Electronics are consistently the most popular holiday gifts, with TVs, tablets, and video games and consoles as other perennial favorites.

According to PriceBlink, a comparison app, Amazon's prices on popular electronics were matched by competing retailers, many of which also offer free shipping at certain price thresholds. Wal-Mart, for example, offers free two-day shipping (like Prime) on orders of $35 or more.

Fans of Netflix who haven't joined Prime yet may also want to consider trying it over the holidays: Amazon Video, which comes free with Prime, has award-winning original shows and movies as well as licensed content that isn't available on Netflix.

For customers stressing out about holiday shopping, joining Amazon Prime seems like a smart move. I wouldn't join it just for Black Friday savings, as Prime may not help you save money. But the convenience of two-day free shipping, and being able to do all of your online shopping in one place at competitive prices, make it worth it. Especially with a free trial, or a $10.99 payment for a single month, Amazon Prime is a low-risk, convenient way to make your holiday shopping easier.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Jeremy Bowman owns shares of, and The Motley Fool owns shares of and recommends, NFLX. The Motley Fool owns shares of and recommends Amazon. The Motley Fool recommends COST. The Motley Fool has a disclosure policy.