Time for a multiple-choice pop quiz.

Over the past decade, the fastest-growing municipality in Lancaster County has been:

A) Manheim Township

B) East Hempfield Township

C) Manor Township

D) East Donegal Township

Go to the head of the class if you picked D. While the first three are among the most populous local municipalities, East Donegal Township has seen its number of residents jump 36 percent from July 1, 2000, to July 1, 2009.

The 2009 estimated population totals for cities, townships and boroughs across the nation — the last to use 2000 census results as a base — were released this summer by the U.S. Census Bureau.

Not far behind East Donegal is nearby Mount Joy Township, which grew 30.8 percent in this nine-year span, and Adamstown Borough, at 28.6 percent. One thing they have in common over the decade is a significant amount of residential construction. East Donegal and Mount Joy townships are in the county's westernmost corridor, where people commute to Harrisburg and York; Adamstown, on the northeastern edge of the county not far from the Pennsylvania Turnpike, is well-known for its antique malls.

Between 2000 and 2009, East Donegal jumped in population from 5,441 to 7,402.

Dennis Drager, vice chairman of the township board of supervisors, understands why. "If I'd want to live anywhere," it would be East Donegal, he said.

There are lots of reasons to recommend it, he said. Even though developments like Castleton are springing up, the township still includes plenty of preserved farmland, so it retains an agricultural character, Drager said.

The fact that East Donegal borders the Susquehanna River and has hiking and biking trails also is a drawing card, he said. "I think that brings people in."

The township is home to several major employers, too, including GlaxoSmithKline, which recently added jobs; Armstrong World Industries; and Donegal Insurance Group.

He said East Donegal is a "bit of a hub" because routes 30 and 283 are easily accessible. Plus, the Amtrak train station in Mount Joy is convenient for commuters, Drager said.

But even with all this growth, the municipality hasn't lost its identity, he said. "We're a little laid back."

Christopher Baumgardner moved into a new townhouse in Castleton, off Route 441, about a year ago. Baumgardner, who previously rented in Ephrata Borough, said he enjoys the outdoors and likes living near Chickies Rock.

He also said Castleton's proximity to routes 30 and 283 makes his daily work commute to Carlisle easier.

According to census estimates, the most populous municipalities in Lancaster County are Lancaster city, with 55,439 residents; Manheim Township, 36,147; East Hempfield, 23,685; Manor Township, 19,713; and West Hempfield, 16,199.

The city was among 10 municipalities that lost population. The others were Akron, Christiana, Columbia, East Petersburg, Ephrata, Manheim, Marietta, Millersville and Strasburg boroughs.

In some cases the decline was quite small. Ephrata had one fewer resident in 2009 than in 2000.

Mount Joy Township, which borders Mount Joy and Elizabethtown boroughs as well as Dauphin and Lebanon counties, saw its population rise from 8,005 in 2000 to 10,468 in 2009.

Township Administrator Casey Kraus said he knew the municipality was growing, but had no idea the total now surpassed 10,000.

"This is such a nice area," he said, with a low crime rate, low taxes and plenty of preserved farms.

Route 283 also runs through the township, and residents can catch Amtrak trains in Elizabethtown as well as Mount Joy, Kraus said.

"This is so centrally located between Harrisburg, York, Lancaster and Reading," he said.

And there's still developable land left within the township's urban growth boundaries, Kraus said.

During 2000-2009, Adamstown's population climbed from 1,202 to 1,549.

Carolyn Friesema, the borough's office manager/treasurer, noted that several subdivisions — including Stoudtburg Village and Brookview — are either fully or partly located in Adamstown, which largely accounts for the population increase.

Many of the new houses also were reasonably priced, so sales were strong even when the economy slowed, Friesema said.

But the Adamstown location definitely helped, she said.

The proximity to the turnpike is great for commuters, Friesema said, and the borough itself has green space, park facilities and a nice community pool.

And so much is within walking distance, she said, even for people with disabilities. Adamstown recently finished putting in curb cuts that comply with the Americans With Disabilities Act, Friesema said.

Adamstown Mayor David Buckwalter also pointed out the abundance of antique markets, and the fact that municipal taxes haven't been raised since 2004.

"All these things made it easier for developers" to sell new homes here, he said.

"It's a nice little borough."