Roger Gilbertson / SpaceX

A Falcon 9 sits on its launch pad at Cape Canaveral, Fla.

Update for 10:35 a.m. ET April 10: SpaceX is looking closely at south Texas as the locale for its third launch pad, following Cape Canaveral Air Force Station in Florida and Vandenberg Air Force Base in California. However, the California-based company says it hasn't ruled out other options elsewhere.

"SpaceX is considering multiple potential locations around the country for a new commercial launch pad," company spokeswoman Kirstin Brost Grantham said in an email. "The Brownsville area is one of the possibilities."

The potential site near Brownsville in Cameron County, at Texas' southern tip,  came to light in the Federal Aviation Administration's notice of intent to move ahead with an environmental impact statement and other regulatory proceedings. The document was published in the Federal Register on Tuesday, and an advance copy was noted on Monday in Clark Lindsey's RLV and Space Transport News.

SpaceX has been planning to build a purely commercial launch site for months. "We do think we need three launch sites in order to handle all of the launch demand that we have been able to get," company founder Elon Musk told me last summer. Musk said he was considering sites in Texas as well as Florida, Puerto Rico and Hawaii, among other locations.

The fact that the Cameron County site will be the subject of a costly environmental study, as well as a May 15 public hearing in Brownsville, suggests that it's a serious contender if not yet the final selection. The FAA's notice says SpaceX would plan up to 12 launches a year from the site, involving its Falcon 9 rocket as well as the Falcon Heavy, which is currently under development. "A variety of smaller reusable suborbital launch vehicles" would also be launched, the FAA said.

Two Falcon 9's have been launched over the past couple of years from Cape Canaveral, and the third one is due for liftoff on April 30 with the International Space Station as its destination. SpaceX's Vandenberg operation will use the Falcon Heavy for military satellite launches. Musk has said most of the commercial launches on SpaceX's manifest would be shifted to the third launch site. "Just as there are Air Force bases and commercial airports ... there's some logic to separation," he told me.

SpaceX's rocket development facility is based in McGregor, Texas, which is about 400 miles north of Cameron County.

The process of approving and building a launch complex could take several years. Already, some of the commenters on RLV and Space Transport News have noted there are a number of oil rigs surrounding the proposed Cameron County site, which could complicate launch operations. The site is also near a wildlife management area and Brazos Island State Park.

Last July, a judge from neighboring Willacy County told Harlingen's Valley Morning Star that an unnamed aerospace company was negotiating with the county to lease a launch site there.

"They have to be close to water, away from populated areas," County Judge John F. Gonzalez Jr. was quoted as saying. "They have to have at least a 3-mile clear zone around the launch site. ... If it doesn't work out here, there are a couple sites in Cameron County. But they would have to buy up some houses there."

If SpaceX's plans for Cameron County are similar to what was being planned for Willacy County, the economic impact could be significant. "They'll be investing up to $50 million and hiring 100 to 200 full-time people, from low-end labor up to electrical engineers," Gonzalez said last year. "Wages will be at least 30 percent above the local norm."

This report was updated to reflect SpaceX's statement that other sites are still under consideration.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.