A Surveyor Looks at the Washington, DC Planning Map
When you read about the history of the city of Washington in the District of Columbia, you are often confronted with the idea that the land on which the new city was to be placed was virgin territiory and a blank tablet. But when you look at maps from before the work began, you will see that many of the main elements in the 1791-2 planning map already existed in some form.
The next images show the estates that once occupied that area, and the roads that existed. Notice the differences in the details in the maps, and imagine that YOU had to draw a map like that from a horseback survey.
Notice that you have Carrollsburg, Hamburgh and Georgetown in the area. Jenkins Hill is near the Capitol location today. The White House is near where we see the word 'Hamburgh'. Below you can see Alexandria and Mt Vernon, George Washington's home. Martha Washington inherited the land across the Potomac from Hamburgh, when her first husband died. Arlington Cemetery lies on that property today. Arnebeck tells us that G. Washington owned 1200 acres within the area that HE chose for the district.
The oblique square you see is the boundary of the District of Columbia. Below you can see that 16th Street (red line) was aimed down the Potomac toward Mt Vernon. Notice in the image above where the ferry road ran all the way from Georgetown to the East Branch. Note especially where three roads came together at Jenkins Hill.
As the story goes, the DC Planning Commissioners asked L'Enfant for a post road that would connect Georgetown to the White House and the Capitol Building, and he gave them Pennsylvania Avenue. Below you can see an architects reconstruction of the 1791 topography of the area, where you can see the ferry road clearly.
Notice that he has marked the locations of the Capitol and the White House. When you look at a modern map of Penn Ave, you can see that it is directed from a point in central Georgetown to the White House and the Capitol, and on to the East Branch. L'Enfant takes the kinks out of the road, and moves the location of where it meets the river a little bit.
As you can see the Capitol Building is north of the straight line of the upper end of Penn Ave between Georgetown and the WH. If you look at the modern map, you can see that that avenue has a bend in it because of the location of the CB. As you can see, the straight line location fell on the steep side of Jenkins Heights.
When you look at the modern map, you also note that the straight line from G'town through the WH points to the location where the real avenue terminates at the river. That is, if the CB had been 600 feet to the south Penn Ave would have been straight all the way from Georgetown to the river.
My straight line hypothesis is that this line represents the diagonal surveying base line for the city layout, and that since the ideal location of the CB fell on the side of a steep hill, they moved it to the nearest (but not the highest near) flat spot). I recommend that they moved directly north, in order to preserve the same east-west distance between the CB and WH. I say that because when you measure, you find that the e-w distance between the WH and the CB is the same as the distance between the two wide points of the pentagram.
Above you can see that Massachusetts Ave parallels Penn Ave, and is like wise bent. It appears to match the location of the upper branch of the ferry road as well. Notice how the bend in Mass Ave is because it is directed to Lincoln Square east of the CB. To straighten Penn and Mass Ave's, we would need to move the CB south, and move Linc Sq east.
You can see that Rhode Island and New York Aves radiate away from 16th Street at the opposite angle to Penn and Mass Ave's, and that the map is symmetrical aorund 16th Street. Note the rhombus that is formed where the two sets of streets cross.