It's happened to all of us: The book you desperately need to unblock your family history research exists, but the nearest library that has a copy in its collection is halfway across the continent. Welcome to the genealogy researcher's classic mountain-and-Mohammed moment.

Fortunately, there's a way to bring the book to you, without embarking on a trip to the library thousands of miles and hundreds of dollars away. It's called Interlibrary loan — ILL for short — and you've probably heard of it, but maybe you haven't actually tried it. The reason so many researchers fail to take advantage of ILL may be that this service is technically a library-to-library transaction. Although it's unclear exactly when ILL was established, the Library of Congress <www.loc.gov> started loaning books as “the nation's library of last resort” in 1902.