But people cross these barriers with increasing ease and regularity. Roads, rails, and tunnels penetrate some of the most imposing mountain ranges. Airplanes span the globe in a matter of hours, information in an instant. And the barriers themselves can migrate. Natural barriers are transient, not eternal.
Some boundaries follow lines of equal latitude or longitude.
Examples include the straight or gently bowed lines which border many Canadian provinces and U.S. states on maps. Even the greatest familiarity with the land, however, is no guarantee that its resources have been identified. As the needs of individuals and communities change, so do the pressures to re-draw political boundaries or to learn to cooperate across them. The location of boundaries is at the heart of the political and social turmoil in Gaza. Classroom Ideas Megan Baker of Nova School, Lacey, Washington, Dr. Sari Bennett of the Department of Geography, University of Maryland, Baltimore County, and the Maryland Geographic Alliance contributed extensively to these classroom activities.