The Russian ruble is the most undervalued against the dollar, by 65%, according to the Economist's measure. A Big Mac in Russia costs 1
On the opposite side of the spectrum, Switzerland's only currency is overvalued against the buck. A Big Mac costs 6.5 francs in Zurich, about $ 6.6, which makes the franc 14% stronger than it should, according to the purchasing power parity theory.
Measured by the ICE US Dollar Index, the buck has gained 0.9% this year, according to Refinitiv. In 2018, it was up 4%. Last year's gains were driven by the Federal Reserve's most active moves to increase interest rates. Higher interest rates make the assets of a country, including its currency, more attractive to investors.
This year's turn by the Fed, which is now expected to cut rates, should weaken the dollar.
Politicians across the spectrum have noted the US dollar's strength versus its rivals is a disadvantage to the competitiveness of the United States on the global market.