Walmart is ending its first-ever car seat recycling event nine days earlier than planned.

The trade-in event, which offers a $30 gift card for bringing an old car seat to nearly 4,000 Walmart stores, now will end Saturday, Sept. 21. The event began Sept. 16 and was originally expected to end Sept. 30.

"Due to the overwhelming response from our customers, we are quickly reaching capacity for this program," Walmart said in a statement to USA TODAY. "In less than one week, we estimate we will collect nearly 1 million car seats – or the equivalent of diverting over 200 million plastic bottles from landfills."

In other words, that means Walmart expects to have given out $30 million in gift cards from this trade-in event.

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"We are thrilled to have worked with TerraCycle and that so many customers and associates participated. Through the car seat recycling event, we’ll help families to keep their kids safe and help reduce plastic waste from landfills," Walmart's statement said. "We look forward to hosting future events supporting the needs of parents and families."

To underline the popularity of Walmart's event, it expects to collect a million car seats in its shortened six-day event – or twice as many as Target did in three years.

Target introduced its first car seat trade-in program in April 2016 and before its recent September event said it recycled half a million car seats and more than 11.9 million pounds of materials. Target gives shoppers 20% coupons on select baby gear in exchange for the seats.

About Walmart's car seat trade-in event

Walmart’s event ends Sept. 21 and all car seat brands will be accepted. All car seats collected will be recycled through TerraCycle.

Bring your car seat to the Customer Service counter during the recycling events at participating Walmart stores, which can be found on the store's website. On Walmart.com, find the closest location by searching by ZIP code.

In exchange, get a $30 Walmart gift card to use in-store or online. The card is subject to Walmart gift card's terms and conditions. In exchange, get a $30 Walmart gift card that “you can use in-store or online to buy items for your baby.”

There’s a limit of two trade-ins per household and booster seats are not eligible for trade in.

Learn more and find locations at www.walmart.com/AboutBestOfBabyMonth.

Follow USA TODAY reporter Kelly Tyko on Twitter: @KellyTyko