As humans, we have a deep need to delineate, so we rely on borders. They can be historical, geological, psychological, but mostly geographical. (What would be the point of an atlas without them?) While it's rare to have an actual dotted line on the ground, there are places where borders take on a unique position or special meaning. Here are five of them in the West - which doesn't really have a border.

1. Port of Entry, San Ysidro, San Diego County

Reportedly the busiest border crossing in the world is at the confluence of California's San Ysidro and Mexico's Tijuana. More than 6 million people cross the north/south border via car, bus or on foot each year. Driving from the United States into Mexico is a breeze, but leave plenty of time for the wait to get back on U.S. soil. 720 E. San Ysidro Blvd.; (619) 690-8800;

2. State Line, Primm, Nev.

What a difference a state line makes: On one side gambling is pretty much card rooms and Lotto picks; on the other, you can play the slots in the grocery store. Primm literally is a stone's throw from the California state line, and with three casinos willing to take your hard-earned cash (Primm Valley Resort, Whiskey Pete's and Buffalo Bill's), there's little need to venture farther into Nevada to get your game on. (702) 386-7867;

3. Strait of Juan de Fuca, North Olympic Peninsula, Wash.

Defined as a channel by the U.S. Geological Survey, the strait extends eastward from the Pacific Ocean between Vancouver Island and the Olympic Peninsula in Washington state. Where the waters begin and end in each country might be a matter of maritime dispute, but orcas don't recognize borders. You can watch them swim from one country to the other during their migratory season. (360) 452-8552;

4. Four Corners Monument, Navajo Nation

On Navajo tribal land where four states come together - Arizona, Colorado, New Mexico and Utah - there's a simple concrete marker that was laid in 1912 to commemorate the spot and redone in 2010 in granite and brass. In recent years, the exact location has been disputed because of developments in GPS technology, but for now, the states and the U.S. Supreme Court have all agreed that, legally, the monument is in the right spot. Six miles north of Teec Nos Pos, Ariz., take Four Corners Road off Highway 160 in New Mexico.

5. Point Roberts, Wash.

The Oregon Treaty of 1846 followed the 49th parallel (which divided the Pacific Northwest). As a result, a chunk of land was sealed off at the southernmost tip of Canada and deeded to the United States. It probably seemed like no big deal at the time to annex a 1,200-hectare parcel jutting into Boundary Bay, but because the 1,300-person community of Point Roberts is actually on American soil, you now have to cross over two U.S.-Canada borders to get there from Washington state.

- By Erin Caslavka Deinzer,