GATLINBURG, Tenn. (AP) - A surge in December traffic in the Great Smoky Mountains National Park kept visits above 9 million for 2011, but by a scant margin.

Figures released by the National Park Service on Thursday showed 9,008,831 visitors last year came to the most-visited of the national parks. The number was down nearly a half-million from the 9,463,538 people who came in 2010.

Park officials said December brought 471,603 visitors as unusually warm weather prevailed. That compared with 342,512 in December 2010 which had harsh conditions. December 2011 visits jumped 37.7 percent, compared with the same month the year before.

Reasons for the 4.8 percent yearly decline were speculative, but park officials said the Smokies might have benefited in 2010 from the Gulf of Mexico oil spill as many vacationers avoided the beaches.

The Park Service said beaches and the mountains tend to draw visitors from the same Midwest geographic region, including Illinois, Indiana and Ohio.

A strong advertising campaign to lure travelers back to the beaches ran in 2011.

Visits to the 397 National Park Service sites nationwide declined slightly last year. Grand Canyon National Park, the second most visited National Park behind the Smokies, dropped by 3.3 percent in 2011 with a total of 4.2 million visits. Yellowstone travel was off by 6.8 percent with 3.4 million.