It probably is not surprising that political drama on Capitol Hill is heightened with Donald Trump occupying the White House. Nor is it surprising that gold and the related exchange-traded funds (ETFs) are benefiting from that increased political uncertainty.

Year to date, the SPDR Gold Shares (GLD) and the iShares Gold Trust (IAU), the two largest U.S.-listed gold ETFs, are each up 11.6%, bolstering the thesis that the yellow metal remains a preferred destination for investors worried about political volatility. If GLD and IAU can hold double-digit gains for 2017, it will be the best annual performances for the gold ETFs since 2011, when the funds barely missed out on annual gains of 10%. (See also: Getting Into the Gold Market.)

Impressively, gold is performing well against the backdrop of the Federal Reserve boosting interest rates. The Fed has increased rates twice this year and is likely to unveil one more rate hike before year end. Lower interest rates favor gold because the commodity does not pay a dividend or interest. "Gold is most correlated with real interest rates (in other words, the interest rate after inflation), not nominal rates or inflation," said BlackRock in a recent note. "While real rates rose sharply during the back half of 2016, the trend came to an abrupt halt in early 2017. U.S. 10-year real rates ended July exactly where they began the year, at 0.47%. The plateauing in real yields has taken pressure off of gold, which struggled in the post-election euphoria."

While equity market volatility has been benign this year, the same cannot be said of Capitol Hill, a theme that is lifting gold ETFs. "Using the past 20 years of monthly data, policy uncertainty, as measured by the U.S. Economic Policy Uncertainty Index, has had a more statistically significant relationship with gold prices than financial market volatility," according to BlackRock. "In fact, even after accounting for market volatility, policy uncertainty tends to drive gold prices." (See also: 3 Positive Chart Patterns for Precious Metals.)

GLD is the world's largest gold ETF, but IAU is not to be ignored. IAU has $8.9 billion in assets under management, a figure that is rising due to its favorable expense ratio. IAU charges 0.25% per year, or $25 on a $10,000 investment, compared with 0.4% for GLD. Since the start of the third quarter, investors have added nearly $212 million to IAU, bringing the ETF's year-to-date inflows total to almost $788 million. That is good for one of the best inflows tallies among all commodities ETFs this year. (See also: Fees Matter With Gold ETFs Too.)