However, it certainly does not explain the weird zig-zag at the point of the dam.
And it doesn't explain why the state line marker on the bridge is not even close to the state line, if that line is really east of the river.
Here is a link to a short article describing the history of Arizona's borders: Arizona Border Article.
Too add to the argument that online maps tend to have bad borders, check out this look at Puerto Iguazu, Argentina. The confluence of the three rivers form the borders between Argentina, Brazil, and Paraguay. However, on GoogleMaps, it is about a mile north of where it should be.
I agree with Aye above, that the problem is with the map. I've always been told that the state line is half way between both shores.
Google maps differs from several of these corners.
Official borders of Arizona
(1) Beginning at a point on the Colorado River twenty English miles below the junction of the Gila and Colorado Rivers, as fixed by the Gadsden Treaty between the United States and Mexico, being in
latitude thirty-two degrees, twenty-nine minutes, forty-four and forty-five one- hundredths seconds north and
longitude one hundred fourteen degrees, forty-eight minutes, forty-four and fifty-three one -hundredths seconds west of Greenwich;
(32º 29' 44.45" -114º 48' 44.53") southwest corner of Arizona
(2) thence along and with the international boundary line between the United States and Mexico in a southeastern direction to Monument Number 127 on said boundary line in latitude thirty-one degrees, twenty minutes north;
thence east along and with said parallel of latitude, continuing on said boundary line to an intersection with the meridian of longitude one hundred nine degrees, two minutes, fifty-nine and twenty-five one-hundredths seconds west, being identical with the southwestern corner of New Mexico;
(31º 20' 0.00" -109º 02' 59.25") southeast corner of Arizona
(3) thence north along and with said meridian of longitude and the west boundary of New Mexico to an intersection with the parallel of latitude thirty-seven degrees north, being the common corner of Colorado, Utah, Arizona, and New Mexico;
(36°59' 56.31532" -109°02'42.62019) Four Corners: precise
(4) thence west along and with said parallel of latitude and the south boundary of Utah to an intersection with the meridian of longitude one hundred fourteen degrees, two minutes, fifty-nine and twenty-five one-hundredths seconds west, being on the east boundary line of the State of Nevada;
(37º -114º 02' 59.25") northwest corner
(37° 0'1.43" -114° 3' 2.14") Google Earth
(5) thence south along and with said meridian of longitude and the east boundary of said State of Nevada, to the center of the Colorado River;
(6) thence down the mid-channel of said Colorado River in a southern direction along and with the east boundaries of Nevada, California, and the Mexican Territory of Lower California, successively, to the place of beginning.
I agree with Aye above, that the problem is with the map. I've always been told that the state line is half way between both shores. ... The confluence of the three rivers form the borders between Argentina, Brazil, and Paraguay. However, on GoogleMaps, it is about a mile north of where it should be.
Having the state line in the river is what I expected (and think I said in the OP.) Pacomartin's description confirms this, and I assume that he obtained it from an official source. I just wonder how/where Google Maps comes up with their map of the border, with turns that obviously don't follow the river. Same puzzlement for the South American borders you mention.
Is Google Maps just screwing things up or do they have some source that should be reliable but is in error?
The obelisks were constructed after the war in the 1850's to mark the border.
Monument #127 is right at the corner in the middle of Arizona (near Nogales border crossing). If you look at it in Google Earth they have something marked monument tank which looks like a parking lot in the middle of nowhere. It's about 1/3 of a mile from where Google shows the corner in the Arizona border.
Monument #127 is bigger than most of them
Well, if you look at the satellite version of the map that you linked, you can see that they still show the intersection of the borders slightly away from where the monument is located in the satellite image, so I don't think that monument-positioning error explains the diagonal section of the border.Quote: Wizard
... Was this a recent thing to put the memorial at the actual point where the four states touch. You may recall they figured out recently the memorial was off by about 20 feet several years ago.
If the Google Maps version of the Utah-Colorado border half a mile farther north is correct (and I have no idea one way or another), then the diagonal adjustment would be necessary in order for there to be a four corners at all. Otherwise, Utah would not reach far enough east to touch New Mexico even at a point.
There was a thread here some time back that discussed a book, I think, that went into detail about the shape of all the states and how they got that way. I never followed up on that book, but I do know that several state borders that appear as straight lines with a casual glance really have some offsets. It is plausible to me that the UT-CO border and the AZ-NM border are at different longitudes for the most part, with a slight adjustment near four corners so that there is a single point of common contact. It is also plausible to me that Google Maps is not so accurate in the details as some of us nerdy, obsessive-compulsive sorts might have hoped. Is there a better, available-for-free, on-line map resource? (Yes, I want everything, and I don't want to pay for it.)