From the outside, Fort George G. Meade seems an inviolable fortress, surrounded by armed guards and tall fences with barbed wire. Few members of the public ever get a glimpse inside the 5,400-acre Army post that is also home to the National Security Agency.

These days, its gates hide a new level of activity as officials work to make the post more secure after the Sept. 11, 2001, terrorist attacks and to accommodate what could be one of the biggest growth spurts in the post's history.

Thousands of additional workers could be based at Fort Meade under a Pentagon plan to realign some military bases. The plan was endorsed last Thursday by President Bush and awaits congressional approval.

Meanwhile, a private company has begun a residential construction project designed to provide 3,100 new or renovated homes on the post over 10 years. And the NSA, which is looking to add 7,500 workers over five years, is experiencing one of its largest bouts of hiring.

The activity is spilling outside the fort. In addition to the existing office parks nearby that are used by defense contractors such as Lockheed Martin and Boeing, more than 1.5 million square feet of commercial space was approved recently by Anne Arundel County for construction. And 3.9 million square feet of development is awaiting county approval.

Plans call for turning Route 175, the two-lane road that runs by the post, into a multi-lane divided highway. Maryland transportation officials have even talked about extending the Metro from Greenbelt to Baltimore-Washington International Airport. That service expansion, which would be designed to improve the link between Baltimore and Washington, would have a stop at Fort Meade.

The bottom line, regional leaders and economists say, is that Fort Meade's expansion is helping to create not just one of the fastest-growing areas in the Baltimore-Washington corridor but also a national military hub.

"This is one of the most progressive areas, in terms of national security, in the nation," said U.S. Rep. C.A. Dutch Ruppersberger (D-Md.), whose district includes the post. "And we have to stay ahead of the curve."

Overseeing the changes at the post are two new leaders: Col. Kenneth O. McCreedy, who became the installation commander in June, and Lt. Gen. Keith B. Alexander, who took over as the director at the NSA on Aug. 1. Alexander was previously the Army's deputy chief of staff. Before that, he served in a variety of high-level posts such as a deputy director for the Joint Chiefs of Staff, intelligence director for the U.S. Central Command and commander of the Army's Intelligence and Security Command.

McCreedy also has an intelligence background. Before and after the Sept. 11, 2001, attacks, he was commanding an electronic intelligence battalion in Kuwait. He also worked for a year as a National Security Agency fellow at Fort Meade.

In his new job, McCreedy said, much of his time will be spent on details more suited to a city manager. Under the Pentagon's Base Realignment and Closure Commission, Fort Meade stands to gain about 5,400 new workers -- a number that post officials said can easily be accommodated.

Meanwhile, McCreedy is working to implement a plan developed by his predecessor, Col. John W. Ives, to make the post more secure.

Though designs have not been finalized, the idea is to move more sensitive operations to the center of the post, where they would have greater protection. That could mean that the fort's golf course, which occupies prime real estate in the middle of the post, could be moved.

"We're beginning to think how we might bring more facilities that require greater security to the interior of the post and push out those activities to the exterior that require less security," he said. "The golf course obviously isn't a high-priority target for terrorists. But NSA could be."

The plan, which looks 30 years into the future, would allow the base to handle an even greater influx than is now projected, said Clemon Wesley, president of the Fort Meade Alliance, a nonprofit that advocates for the post.

With a staff of about 30,000 at the installation now, "we think we could accommodate another 30,000," he said.

Work is underway on the post's ambitious housing development project. Already this year, Picerne, the private development company that the Army has hired to oversee the project, has built 419 homes. Over the course of the project, the company plans to build five new neighborhoods on the post, each with 500 to 700 homes. The company has a 50-year agreement with the Army to manage and lease the properties.

Outside the post, more residential development is on the way. About 4,000 housing units have been approved around the post and 1,100 are still being reviewed, according to the county.

Business parks hoping to lure defense contractors are also popping up.

On a recent rainy day, some of the region's top political leaders gathered to herald the expansion of Route 175 and the infusion of $12.5 million from the federal government to get the project started.

Ruppersberger said that while it may be difficult to get excited about a road project, this one signals the growth to come. The area around Fort Meade and the NSA is becoming a focal point for the Defense Department, he said, and a focal point for intelligence.

As the NSA and Fort Meade grow, so will the surrounding area, officials said. More workers mean more cars, and more cars require wider roads -- which is why, officials said, the road is important.

"Right now, Route 175 is a 60-year-old country lane that is serving as a major artery for Fort Meade and NSA," said U.S. Rep. Benjamin L. Cardin (D-Md.). "It's not up to the job, and it's time that we modernize it and bring it into the 21st century."

Builders prepare to lift roof frames, above, as others raise walls, left, in the Meuse Forest neighborhood at Fort Meade, part of a plan for 3,100 new or renovated houses over 10 years. A military base realignment plan and National Security Agency expansion could add thousands of workers at the post.