10. Geodetic markers corresponded to a new geospatial notion of legibility, but are strewn across the state as far more minor monuments. As the obelisks made the border manifestly present in the landscape, the survey markers the USGS has since planted in the ground, over a million at set points on the peaks of mountains, sites of elevation and surveying, are an entrancing if opaque signifiers in the past bench marks of property lines, city planning, or earlier attempts at transcontinental triangulation, spatial address with alphanumeric codes: they promise and promote the public utility of the legibility of the land, as did the border markers that often began by including bilingual inscriptions. The legibility of the surface of the lower forty-eight still depends on attempts to reconcile the dangers of linear distortion of projections on distances at uneven elevations–either low-lying regions near the Great Lakes, for example, or the elevated areas expanding cities like Denver, where discrepancies between coordinates and natural topography might create underestimates of property.
The new spatial addresses offer alphanumeric codes overlain on the Universal Transverse Mercator better to orient ourselves along a uniform grid, superimposed over boundary lines of state sovereignty or county lines.
The degree of linear distortions that existed at the border, in Pima County, was low, but must have been a question of concern for the Border Patrol officers who patrolled the region.