Answer:
When economists say that the US economy has a higher safe speed limit than it had previously, it means that:
Overheating the US economy does not produce high inflation.
Explanation:
The US economy is being overheated through rapid economic expansions. Some of these expansions are engendered by rapid technological changes. The US government also often indulge in aggressive economic expansions by ensuring maximum employment and capacity utilization. But these measures have been found to not distort the economy with high inflation rates. As a result, an economist can conclude that "the US economy has a higher safe speed limit than it had previously."