A few years back I was on the International Boundary Commission's mailing list. It was great to get their annual reports full of photos and great information on that year's accomplishments along US-CA. However, around 1999, they began requiring paid subscriptions for their report, so I was dropped from their list because I didn't subscribe. I learned a lot from my few years on their list reading the reports--which I still have by the way.
Recently someone (maybe Zoomer at Idaho-BC) asked about why the US-CA border vista wasn't cleared nor was there an apparent marker at a point where he crossed. Here's what I believe the situation was. There was a border marker somewhere near the crossing point. There always is. It might have been small. The IBC uses several different forms of boundary marker along US-CA. These range from one-meter-high obelisks made of cement and covered with pretty, small, colorful pebbles or one meter stainless steel obelisks. The latter are the most recent. They also use short obelisks about eight to ten inches tall grounded in a cement square base. Perhaps this was the case at that point but somewhat obstructed by vegetation. At some points along the border, there is simply a brass surveying disc embedded in cement, which would not normally rise above the grass line. This might account for the lack of a marker.
Now about the vegetation. International law (US-CA) requires the vista to be cleared of all obstructions (human and natural) for ten feet on either side of the border. However, the IBC is very budget conscious and staffing is limited (learned all this from the report). So, each summer, and only in summer, three-five IBC crews are dispatched to some point at the border, where they spend all summer clearing vegetation with bulldozers, herbicides and chainsaws, and repairing border markers. There are rarely more than 30-40 people every year working along this huge border, and only a small fraction of the line gets cleared every year. If I recall correctly, its not many kilometers a year. Therefore, there are many places along the border that don't get much attention, but say every 10 or 15 years or so. In the meantime, vegetation has a considerable amount of time to re-grow on the vista.
Nowadays, however, I understand that the IBC is beginning to use herbicides that have a more long-term effect, i.e., that permanently stunt the growth of vegetation for years to come.
These facts I think explain the experience that Zoomer (or was it someone else) had on the border recently.
Dallen