As of August 2019, long-term interest rates were falling faster than short-term rates, inverting the yield curve.

Judge by US Treasury yields over the months leading up to mid-August 2019. True: long-term yields (such as the 10-year or 30-year) fell by more than short-term yields (3-month or 2-year), and a standard spread (10-year minus 3-month, or 10-year minus 2-year) was inverted or reached inversion. Mostly true: both hold for one standard pair but not the other, or the inversion was marginal or brief. Mixed: the curve inverted, but mainly because short rates rose or held while long rates were stable, or long rates fell faster but no standard spread inverted. Mostly false: long rates did not fall faster than short rates and the curve was not meaningfully inverted, but some minor segment inverted. False: the curve was not inverted on any standard measure, and short rates fell faster than long rates.

Set before the research began.

1. E1 Key yield curve inverts to worst level since 2007, 30-year ... CNBC · 27 August 2019

   “At around 3:30 a.m. ET, the yield on the benchmark 10-year Treasury note, which moves inversely to price, was trading down at 1.501%, while the yield on the 30-year Treasury bond edged down to 2.012%.”

2. E2 Key yield curve inverts to worst level since 2007, 30-year ... CNBC · 27 August 2019

   “Investors remain attuned to the critical spread between the 10-year and 2-year yield, which inverted further on Monday as an upcoming supply of $113 billion in fixed rate, coupon-bearing shorter-maturity Treasury debt outweighed the perceived thawing of trade tensions”

3. E3 What Is the Yield Curve? Congressional Research Service (via EveryCRSReport)

   “As the figure illustrates, the yield curve inversion has occurred because short-term rates have risen and long-term rates have declined.”

4. E4 What Is the Yield Curve? Congressional Research Service (via EveryCRSReport)

   “The flattening of the yield curve since November 2018 has been driven by the 1.5 percentage point decline in the 10-year yield over that period.”

5. E5 [PDF] Yield Curve Inversion: Evaluation and Implications Korea Capital Market Institute (author: Baek, In Seok) · 24 September 2019

   “The yield curve on 10-year and 2-year Treasuries inverted in August 2019, and the deteriorating U.S.-China trade war is viewed as a major factor in play here.”

6. E6 [PDF] Yield Curve Inversion: Evaluation and Implications Korea Capital Market Institute (author: Baek, In Seok) · 24 September 2019

   “This time, the spread between 3-month and 10-month Treasuries inverted in May 2019.”

The Congressional Research Service says the yield curve inverted because short-term rates rose while long-term rates declined (E3). It also says the flattening since November 2018 was driven by a 1.5 percentage point fall in the 10-year yield (E4). That means long rates fell by more than short rates. On the spreads, the Korea Capital Market Institute paper dates the inversion of the 3-month spread (against what the quote calls "10-month" Treasuries) to May 2019 (E6) and says the 10-year/2-year spread inverted in August 2019 (E5). CNBC reports that the 10-year/2-year spread inverted further in late August (E2).