Two newspaper companies interested in how social media could affect their businesses are now investors in , a startup focused on social media solutions.

American City Business Journals, which is based in Charlotte, N.C., led the $4.1 million “B” round of financing in ThePort. Lee Enterprises also participated.

ThePort, which launched in 1999, operates on a software-as-a-service model.

“We recognize social media as a key driver for the future of online publishing and a way to stay a step ahead in our ever-changing business landscape,” said Ray Shaw, chairman of ACBJ. “We believe ThePort’s platform, management team and proven track record of success will enable it to become one of the market leaders in the social media platform space and we’re thrilled to partner with them.”

ACBJ operates weekly business newspapers and related Web sites across the country, including Atlanta, Research Triangle Park, N.C., Charlotte and the Triad.

ThePort said the funds will be used for expanded sales, marketing and business development efforts plus additions to its technology.

The company augments existing Web sites with features similar to MySpace, FaceBook and YouTube and focuses on content aggregation as well as self-publishing for users.

Other investors included Bob Cramer, CEO and co-founder of ThePort, and angel investor Robert Jetmundsen. Cramer, an active entrepreneur and philanthropist in Atlanta, has been CEO since January of 2006.

“It’s clear that static online experiences are no longer enough for today’s consumers, and ThePort opens the door for organizations to leverage social media across a range of relationship-building, marketing and branding efforts,” Cramer said in a statement. “This significant round of funding, particularly in light of the current economy, validates ThePort’s market offering and delivery model.”

ThePort customers include CARE, Arthritis Foundation, Lee Enterprises and Sierra Club.

ACBJ is part of Advance Publications.