The EIA reported that total U.S. propane/propylene inventories increased by 3.1 MMbbl for the week ended September 4, exceeding the industry-expected build of 920 Mbbl and the average build of 1.9 MMbbl for the week. The increase lifted stocks to an all-time high of 110.5 MMbbl (red line in the chart below). Stocks are 12.8 MMbbl, or 13%, above the same week in 2025 (blue line); 11.4 MMbbl, or 11.5%, above the five-year maximum; and 22.2 MMbbl, or 25%, above the five-year average (green line). Inventories remain on track to approach 119 MMbbl by early October before seasonal draws begin. That would be approximately 13% above the 2025 high of 105.4 MMbbl recorded in November 2025.
The increase in total U.S. inventories was driven primarily by PADD 3 (Gulf Coast), which added 2 MMbbl and accounted for roughly two-thirds of the nationwide build. The increase lifted regional stocks to an all-time high of 70.2 MMbbl (red line in the chart below). Inventories were 12 MMbbl, or 21%, above both the same week in 2025 (blue line) and the previous five-year maximum and 20.2 MMbbl, or 40%, above the five-year average (green line). Combined with the 657-Mbbl increase in PADD 1 (East Coast), the two regions accounted for approximately 86% of the nationwide build. PADD 3 now holds nearly 64% of total U.S. stocks, highlighting the concentration of inventories along the Gulf Coast.
