Sailors from many nations had scouted and mapped the Atlantic shoreline for a century before the English began to colonize North America in the early 1600's. The sailors could measure latitude in the 17th Century, but it was not until the late 1700's that the English created the technology to measure longitude (a clock that could travel on a ship, and measure the time differential between the ship's location and Greenwich).
Most of the North American continent was still "terra incognita" or unknown land to the Europeans throughout the 1600's. That is why the early Virginia maps have reliable information on Virginia's latitude and Chesapeake Bay, mixed in with wildly hypothetical information about the longitude and the lands west of the Fall Line. Without longitude information, early explorers did not understand how far west the North American continent stretched.
The mythical Northwest Passage is still on John Farrer's map. On the far right, he mapped the mythical Northwest Passage water connection between the Atlantic and Pacific (Sea of China and the Indies) oceans.
According to John Farrer, the Hudson River connects to the Pacific Ocean,
just on the western side of the Blue Ridge
rosette showing north (to the right)
on John Farrer's 1667 map
Source: Library of Congress
Northwest Passage on John Farrer's 1667 map
Source: Library of Congress
If that water passage had actually existed, then the cost of shipping between Asia and Europe would have been dramatically reduced, and the Panama Canal would not have been necessary. For 150 more years after John Farrer's map was published, explorations continued for a low-cost water connection across the North American continent. Only after two Virginians, Lewis and Clark, returned in 1806 from their journey across the continent was clear that the headwaters of the rivers of North America did not offer an easy opportunity for a canal to connect the Mississippi River with the Pacific Ocean.
Look closely at the numbers on the very bottom of John Farrer's map, however, and you can see that the latitudes for the mouth of the Chesapeake Bay are relatively accurate.
That knowledge of latitude colored expectations of what would be discovered in the New World that was still unexplored by Europeans. Those Europeans knew where the 36th degree parallel of latitude crossed Europe. The Europeans assumed the climate and crops in Virginia might be comparable to what they experienced at 36° north latitude around the Mediterranean Sea. That's why the early colonists tried to plant oranges in Jamestown - after all, oranges grew in Spain, at the same latitude in Europe.
When John Smith and John Farrer published their maps of Virginia in the 1600's, they oriented "west" rather than "north" at the top of their documents. When eyes of modern readers move from the bottom to the top of their old maps, the eyes are traveling to the west - inland. The maps are oriented for a sailor approaching the East Coast of North America in the 17th Century.
In contrast, almost all the maps published in the 21st Century are oriented so north is at the top of the map. Maps on a wall have north at the top, closest to the ceiling. That convention makes it easy to confuse "north" with "uphill" and "south" with "downhill" - so think twice, and don't assume North=Up.
For example, the Shenandoah River flows north from Augusta County towards its confluence with the Potomac River at Harpers Ferry. The Shenandoah River does not defy gravity and flow uphill. The Shenandoah River flows "down the valley," downhill towards Harpers Ferry. Travelers going from Harpers Ferry south to Staunton are going "up the valley" - at least in regards to elevation.
Modern mapping tools, including Global Positioning System (GPS) technology, allows users to trace their path as they drive in a car. However, GPS units with millimiter accuracy thanks to satellite and cell tower links are only as accurate as their underlying maps. When roads change, GPS units end up being... wrong. Drivers can be instructed by navigation systems to go in the wrong direction on a divided highway, when a two-lane road is expanded to four lanes but old maps still tell drivers to "turn left" prematurely.
When the Virginia Department of Transportation built a new interchange for Route 17/Route 29 at Opal in Fauquier County, drivers continued to go to the old intersection and perpetuated congestion in the left-turn lanes. The VDOT District Administrator noted that modern drivers were more focused on out-of-date maps encoded in their electronic mapping tools and not paying attention to the real-world:1
the rose on John Smith's 1612 Map of Virginia had 32 points separated by 11.25 degrees (in contrast to 36 lines separated by 10 degrees on modern compasses)
Source: Library of Congress, Virginia / discovered and discribed by Captayn John Smith, 1606; graven by William Hole
Source: Wikipedia, created by Karl Musser based on USGS data
1. "Motorists still confused about Opal intersection," Fauquier NOW, January 14, 2014, http://www.fauquiernow.com/index.php/fauquier_news/article/many-motorists-still-confused-about-opal-intersection (last checked February 12, 2014)