This year's Prime Day was the single biggest shopping day in Amazon history

Amazon chalked up some big numbers on Prime Day this year.

The marathon discount event marked the single biggest day of sales in the company's history -- even surpassing more established shopping holidays like Black Friday and Cyber Monday, Amazon said Wednesday.

Total sales eclipsed those of the same 30-hour period last year by around 60 percent, though the previous Prime Day only spanned 24 of those 30 hours (Amazon opted to extend it this year) and involved three fewer countries. The site also saw 50 percent more visitors.

Prime membership sign-ups also broke a record with more people joining than on any other day in the history of the program.

The Amazon Echo, its cylindrical digital assistant for the home, was the top-selling item of Prime Day in the United States as of Tuesday morning, according to CNBC. By the end of the day, its miniaturized cousin, the Echo Dot, had snagged the top spot. Amazon had halved the Echo's price to $90 and cut the Echo Dot's from $50 to $35 for the occasion.

The performance isn't much of a surprise considering how aggressively Amazon discounts and promotes its own electronic products each time the contrived date rolls around. Other big sellers this year included Amazon's Fire 7 tablet and the Amazon Fire-edition Element .

Even by the company's own standards, though, the Echo was a big sales hit this year. Amazon said it a sold a total of seven times as many Echo products this year as the same period last year. A source told TechCrunch it was selling "thousands per minute."

Among the most popular deals without the Amazon stamp were 23andMe DNA tests and Senso Bluetooth headphones. And as far as sales by category, tech, home goods, and cooking-ware won the day.

Just hours into the annual promotional holiday -- which was extended into the preceding night this year -- Amazon had already declared it a success, vaguely boasting of customers shopping at "record levels" without elaborating on what exactly that meant. The company did not immediately return our request for clarification.

Amazon's heavy focus on its own gadgetry makes a lot of sense investment-wise. Even if it sells these products at a loss, they still provide valuable avenues through which it can insert its other business tentacles into people's lives.

For instance, Amazon now sets the default choice to its own in-house brands when shoppers ask Alexa -- Amazon's equivalent of Siri -- to order, say, batteries, provided they've bought them in the past. Brands are already experimenting with sponsored messages within Alexa, a capability that will no doubt be eventually folded into Amazon's burgeoning ads business.

As some analysts predicted, Amazon also took the promotional day as an opportunity to plug some of its newer apparel and food private labels that customers may not yet be familiar with. Prime-exclusive clothing -- a category that encompasses Amazon's new stable of fashion lines -- and grocery labels like Wickedly Prime snacks and Happy Belly coffee were all marked down as much as 50 percent.

Even as competitors do their best to undercut the flagship promotional period, it seems Amazon still owns the day.

Updated to include stats for the whole event.