A vote that could redraw the map of Eastern Europe by joining Crimea to Russia has professional cartographers like Juan Valdes on high alert.

In the wake of a referendum scheduled for Sunday, Valdes will likely convene a 10-person committee at the National Geographic Society in Washington, D.C., to determine how the region should be depicted on thousands of print and digital maps. Russia's drive to annex Crimea, a region transferred to Ukraine by the Soviet Union in 1954, has drawn condemnation from the United States and Europe, which have threatened to impose sanctions if Moscow doesn't back down. On Friday, Russia warned that Ukraine's government has lost control of the country.

While redrawing maps to reflect new boundaries is simpler in an era of electronic publishing, doing so is as politically charged as ever. In 2010, an error by Google Maps helped trigger a border dispute between Nicaragua and Costa Rica. Should the reunification be approved, mapmakers risk legitimizing one side over the other if they redraw Russia's boundaries to include Crimea, and the United States and the United Nations refuse to recognize the vote result.

"Maps instill a lot of passion in people, individuals, nations," said Valdes, director of editorial research, whose honorary title is The Geographer. "So we have to be very cautious. We have to make sure that we deal with the reality of the moment."

Unless they are propagandists, cartographers are typically a conservative bunch, according to Jim Akerman, curator of maps for Chicago's Newberry Library, whose collections range from ancient maps to almost every atlas, road and railroad map published by Rand McNally.

"It matters where maps are made," Akerman said. Some Russian mapmakers may be quick, following the plebiscite, to redraw borders to reassert a Russian claim to the territory dating to Catherine the Great, he said. "Others are very slow to make changes unless they're supported by treaties."

Google's mapping service uses broken lines to delineate disputed territories like Abkhazia — which broke away from Georgia in 2008 — Kosovo, Kashmir and disputed boundaries between Egypt and Sudan.

When dealing with territorial disputes, most U.S. mapping companies and commercial cartographers take their direction from the State Department.