Governments need money in order to conduct their business affairs, and therefore bonds are issued to the general public as well as being available to other sovereign nations for investment. These individuals, investors, bond funds, and nations purchase these bonds based on their perceptions as to their overall value and their worth, and because the US Treasury market is open, liquid, and actively traded, the corresponding bond yields are reflective of the true perception by the public of its actual worth. At the current time, the 10-year treasury yield for United States bonds is approximately 2.25%, which is, and has been, at generational lows for the past few years, in fact, you would have to go way back to 1947 to see rates that are comparable to what we have at the present day.
The fact that rates are low may be good, or it may be bad, depending upon which side of the fence that you are sitting on. From a borrower perspective, low treasury yields, equate to significantly lower borrowing costs for the US government, which means that the US government payments to service this debt, has been reduced over recent years by billions upon billions of dollars and that as part of our national debt, the interest payments as a percentage of that debt, have fallen substantially. Again, that is quite beneficial for the US government as it has consistently run up massive deficits over the last fifteen years, however, the counterpoint to this is that those entities that have previously relied on US Treasuries for their sustenance via treasury bonds, or money market funds, or savings account, have seen their yields been decimated, meaning that this investment vehicle is not providing the steady income stream that had once been so reliable.
There are many factors that influence the US Treasury rate, of which, the two most important ones are inflation and economic growth. While the United States publishes all sorts of figures in regards to inflation and to its economic growth, regretfully, governments have a way of putting forth the numbers that favor the perception that they are trying to sell. However, those that are in the know, vote by their actions and their investments as to whether they believe these "official" government numbers, and by virtue of the US 10-year Treasury yield being so low, clearly, those investors believe that inflation and economic growth for America are considerably lower, than a country pretending that we are in our sixth year of economic expansion.
Another point about 10-year treasury yields is that this is a world that is international in nature, so that, if yields are low in America, they may well be higher in other countries, which, in fact is the case. For instance, Mexico's 10-year yield is at 6.07%, and Brazil's rate is at 13.65%, which appear to be rates that would entice the uninitiated, but both of these countries have real reasons for these rates, so that the net real gain for investing in these bonds may be ephemeral. On the other hand, mature and stable countries, such as Japan and Germany, have 10-year yields that are at less than 1%, which makes the US Treasury rate look almost frothy in comparison and there lies the rub. Almost a day doesn't go by, without some pundit pontificating about how the Fed is going to raise its target rate, and therefore US Treasury yields will rise, but in fact, even if this was to occur in the near future, US Treasury yields, would hardly budge, or if they did, it would only be transitory, because the truth of the matter is that the US economic conditions have much more in common with countries such as Germany and Japan than they do with Mexico or Brazil.
The US economy suffers from both anemic growth as well as persistent deflationary pressures, both of which will keep US Treasury yields from liftoff in the short-term foreseeable future.