Judging from last year’s head count in the National Park System—a record 307.2 million—you can pretty much be assured that many parks will be even more crowded this summer as the National Park Service Centennial is celebrated.

The sailing ship Friendship of Salem is a popular attraction at Salem Maritime National Historic Site, but visitors to the park in coming months shouldn't be concerned if it appears the vessel has been "demasted." Removal of sections of the masts and rigging began last week as part of a two-year project to inspect key parts of the ship, and make any repairs that are needed.

What condition are the national parks in? That's an easy, and important, question to ask, but one not always easily answered.