Amazon.com is adding 7,000 jobs in 13 states – including South Carolina – as it beefs up staff at the warehouses where it fills orders, and in its customer service division.

The company says it will add 5,000 full-time jobs at its U.S. distribution centers, which currently employ about 20,000 workers who pack and ship customer orders.

The world’s largest online retailer has been spending heavily on order fulfillment, a strategy meant to help the business grow, but one that has also weighed on profit margins. The company said last week that it lost money in the second quarter, even as revenue increased.

Distribution center jobs are available in Phoenix; Middletown, Del.; Patterson, San Bernardino and Tracy, Calif.; Indianapolis and Jeffersonville, Ind.; Hebron, Ky.; Breinigsville, Pa.; Charleston and Spartanburg, S.C.; Chattanooga and Murfreesboro, Tenn.; Coppell, Haslet and San Antonio, Texas and Chester, Va.

Amazon said President Barack Obama is scheduled to visit the Chattanooga facility on Tuesday. No public schedule was yet posted on the White House website for Tuesday, but the president made what was billed as a major speech on the economy last week, and brought the topic up again in his weekly Internet and radio address on Saturday.

The company is also adding 2,000 jobs in customer service, including full-time, part-time and seasonal. Jobs are available in Winchester, Ky.; Grand Forks, N.D.; Kennewick, Wash. and Huntington, W.Va. Work from home positions are available in Oregon, Washington and Arizona.

Amazon plans to open five more facilities this year, after adding 20 last year. Warehouse expenses have more than doubled during the past three years, as Chief Executive Officer Jeff Bezos opens centers full of products closer to consumers in order to reduce shipping costs and speed up delivery. Higher spending contributed to Amazon’s surprise net loss for the second quarter as the online seller continues to fuel revenue growth at the expense of profits.

“As we get closer and closer to customers with fulfillment, we have seen growth,” Amazon Chief Financial Officer Thomas Szkutak said on a conference call July 25.

That growth is also being driven by Amazon Prime members, who pay $79 a year in exchange for unlimited two-day shipping and access to streaming video, Szkutak said.

“Because of our fulfillment logistics capability, we’ve been able to offer Prime broadly,” Szkutak said.

Subscribers to the shopping program spend three to four times more than those who aren’t members, according to Colin Sebastian, an analyst at Robert Baird & Co. in San Francisco who rates the stock the equivalent of a buy.

Amazon’s distribution-center costs are driven in part by wages. Median pay is 30 percent higher than “people who work in traditional retail stores,” the company said. That pay doesn’t include stock grants available to full-time employees, which have added an average of 9 percent to base pay annually during the past five years, Amazon said.

More information is at www.workatamazonfulfillment.com and www.amazon.com/csjobs.