The new headquarters has 15,494 square feet of usable space on two floors in the building, compared to about 12,000 square feet in five buildings at Ferry Hill.
The headquarters moved because the park's operations outgrew its historic home, and to be closer to Interstate 70. The interstate provides quicker access to Washington - where the National Park Service's headquarters is - and to various points along the 185-mile-long canal, Park Superintendent Doug Faris said.
The old offices were cramped and there were electrical problems, he said Friday. The new offices have three conference rooms while the old offices had just one, park officials said.
There are 47 employees working at the headquarters but that number may increase by five or six in the next five years, Faris said.
The park has a 10-year, $2.96 million lease for the property. If the park used the property for the full 20 years, the lease would cost almost $7.3 million.
The money comes out of the National Park Service's budget.
Park officials want to turn Ferry Hill into an interpretive and educational draw for the public. It could take up to five years to complete the estimated $1.5 million project to rehabilitate the house and open many historic exhibits, Faris said.
From 1 to 5 p.m. on Saturdays and Sundays starting in July, there will be interpretative displays, historic photos and other artifacts available for public viewing at Ferry Hill.
The main plantation house was built around 1810 by John Blackford. Ferry Hill got its name from the river ferry franchise Blackford bought in 1816, according to park history. The grounds and house overlooking the Potomac River were occupied by the Union and Confederate armies during the Civil War.
When the planned move was announced in July, the office of U.S. Rep. Roscoe Bartlett, R-Md., questioned the process resulting in the lease. At the time, Sallie Taylor, Bartlett's deputy press secretary, estimated the congressman's offices had received at least two dozen inquiries about the lease.
Taylor could not be reached for comment Thursday or Friday.
The federal agency that handled the lease refused to release the overall bid results.