With the merger of Continental and United airlines a big step closer to reality now that the federal government has given its blessing, the next big hurdle will be a pair of special shareholder meetings next month.

Both companies have called for shareholders to weigh in on September 17 on the proposal that would give Continental shareholders 45 percent of the new entity, while shareholders of UAL—United Airlines parent company—will own 55 percent.

On Friday, the Antitrust Division of the U.S. Department of Justice said it had completed its review of the proposed merger and had approved the marriage.

"The completion of DOJ's review is an important step on our journey of creating the world's leading airline, benefiting our customers, co-workers, communities, and stockholders," said Jeff Smisek, Continental's chairman, president, and chief executive in a statement. "The DOJ's decision permits us to clear one of the last regulatory hurdles to closing our merger."

Houston-based Continental and Chicago-based United announced an all-stock merger on May 3. The combined company will be headquartered in Chicago, though it will be largely led by Continental executives.

As the Continental-United merger moves ahead, it's causing a handful of ripple effects that business travelers may want to note:

—Southwest Airlines is adding 36 slots at Newark Liberty International Airport since United-Continental is trying to ease some of its presence at Newark, one of Continental's primary hubs. Before the deal, Southwest's only real presence in the New York metro area was about a half-dozen slots at LaGuardia Airport in New York City.

—At least one lawmaker isn't happy with the developments. Representative James Oberstar, the Minnesota Democrat who heads the House Transportation Committee, wants to push for the re-regulation of the airlines as a way to foster competition. "When Congress deregulated the airlines in 1978, we were promised better service, added competition, and more choices for consumers. With the United-Continental merger, our domestic carrier fleet will have shrunk to four network carriers," Oberstar said in a statement. "Can a US Airways-American Airlines merger be far behind?"

—As the merger moved forward, aviation experts said it was difficult to say right now if airfares would rise. "We are losing another airline, so of course competition is going to be lessened," Terry Trippler, an airline expert who runs the travel site RulestoKnow.com, told MarketWatch Radio. "It will benefit in the long-run international travel, international passengers with more connections to more cities on one airline," Trippler said, explaining that besides United-Continental, the United States would have two other major global airlines: Delta Airlines, which has merged with Northwest, and American Airlines.