Editor's note: The Traveler's Essential Friends project this summer has been highlighting the great value that national park friends groups bring to the National Park System. And they manage to do so with charitable dollars from readers like you. But you should do some homework when deciding where to send your dollars, as Dr. Jacqueline Vaughn points out in this guest column addressing charitable giving to friends groups.

Growing up in San Diego, the only national park I visited more than once was Yosemite, and it has always held a special place in my heart. In 1997, I decided it was time to revise my estate plans and asked my attorney what I needed to do to bequeath money to the park.

With a new job and a strongly-held philanthropic ethic, I also decided I wanted to make a contribution while I was still alive. So I started looking for the address and tax ID number the attorney needed so I could start giving away my legacy sooner rather than later.

Sounds simple, right?

Google wasn't available back then, so I tried using the library and the Internet to find out where I could send my check. Searching for "Yosemite National Park" brought up all kinds of choices: a website for the park itself, the Yosemite Fund, a Yosemite Natural History Association, the Yosemite Association, the Yosemite Museum Association, the Yosemite Institute, and Friends of Yosemite Valley.

Looking further, I learned I could donate to Yosemite through the National Park Foundation, or to the park superintendent. I could support the park through the National Parks Conservation Association, or support one of the NPS partnering corporations.

Look on Google now, and the Yosemite Fund is now the Yosemite Conservancy. There are links to sites like eParks, or you can click on causes.com, or iGive.com. You could vote for money to be given to your favorite park through a click and vote campaign, like last year's contest to award $1 million from lowes.com.

Channeling Your Inner Philanthropist

So how do you channel your inner philanthropist to make sure your money goes to the right place, and for a purpose you personally want to support? If you click on the newly remodeled National Park Service website, you'll be urged to get involved by donating directly to a park (there's a place to search for your favorite by name, state, or zip code). There's also a suggestion to donate to a park "friends group," to make a purchase at a park bookstore, or to give to the National Park Foundation, "our Congressionally-chartered national philanthropic partner."

Many park units depend on friends groups for financial support, and there are currently 185 to choose from, including the new Dunes National Park Association. Three-quarters of the organizations have been established since 1980, and most support parks in the Northeast and mid-Atlantic states. About 96 percent have non-profit 501 (c) (3) status, which means your donation is tax deductible. But not every park has a friends group, and some groups support more than one park.

Valuable Help

Friends groups are essential to some parks' operations, especially for major projects and capital campaigns. The Statue of Liberty-Ellis Island Foundation is raising $20 million for the Peopling of America Center that will expand the story of immigration at Ellis Island, and Friends of Acadia hopes to raise $9 million to maintain the park's footpaths. The Trust for the National Mall has embarked on the largest public/private partnership in NPS history, seeking $350 million in donations.

But most park friends operate on a much smaller scale, and some support parks in other ways besides fundraising. Friends of the Apostle Islands National Lakeshore, for instance, has raised about $200,000 since their inception in 2002, with most donations funneled toward restoration of the Raspberry Island boat house.

At Arizona's Tumacacori National Historic Park, the friends group is hoping to compile and sell a recipe book to raise $2,000; over the last few years, money has supported Junior Ranger Day, a, a bench in the historic orchard, and orchard maintenance equipment. Friends of Glacier Bay does not seek members or conduct fundraising activities at all because the national park receives considerable income from fees charged to cruise ship visitors. Some groups have reported no financial contributions to the park they support.

Do Your Homework

Potential donors are advised to do their homework before writing a check, since friends groups come and go, names change, and some run into financial and organizational difficulties that may or may not make the headlines. A donation to a small group may bring you a bigger bang for your charitable buck, while a donation to the National Park Foundation can go to the organization or be directed to a specific park or campaign.

But donors beware and avoid the confusion I faced in revising my will. Check out the NPS website, which usually identifies an official fundraising partner, and then see if the group has an annual report. Charitable watchdog groups, including GiveWell and GuideStar, can provide ratings and information you won't see in an annual report or on a website, such as the amount of money spent on the group's administrative costs or fundraising instead of going to the park.

Yes, the Yosemite Conservancy is still in my will, and I occasionally respond to one of their direct mail solicitations. I read their annual report and monitor what others have to say about them. I'm considering a donation to a group that needs seed money to get started, and decided not to give to another park's Friends group that pesters me with too many online appeals for my limited donor dollars. Like any good philanthropist, I manage my donations carefully, and urge you to do the same when supporting our national treasures.

Jacqueline Vaughn is Professor of Politics and International Affairs at Northern Arizona University, and currently is conducting research on philanthropy and the national parks, with a focus on friends groups and cooperating associations.