How this is built
Methodology
What data The Fill Line pulls, where it comes from, and how often it refreshes.
What we pull, and from where
- Residential and wholesale propane prices come from the US Energy Information Administration's weekly heating-season price survey, published October through March. From April through September the survey publishes nothing by design, so off season the price pages hold their final surveyed readings, labeled as end-of-season prints.
- Inventories, supply, production, exports and demand come from EIA's Weekly Petroleum Status Report, published weekly year round.
- The Mont Belvieu spot is EIA's daily hub price series, which trades year round. EIA also publishes the same hub price at monthly frequency, which is what the long-horizon and off-season charts draw.
- EIA's Short-Term Energy Outlook, the agency's own published monthly outlook for propane prices, inventories and supply. Where the site cites it, it is always labeled as EIA's forecast, with attribution, never as ours.
- Propane-heated households by state come from the US Census Bureau's American Community Survey house-heating-fuel table, the annual reference data behind the state pages.
- Heating degree days come from NOAA's Climate Prediction Center, published weekly.
How often
The pull runs weekly, ahead of the Wednesday brief. Each pull covers a trailing window, not just the newest week, so a missed run backfills on the next one. Every data page carries two dates: "data through" is the newest reading in the data itself, and "page updated" is when the page was last rebuilt. During the April-September survey pause the price pages' data date sits at the end of the season, which is the freshest survey data that exists.
For how to read the numbers once they are in front of you, see how to read this.
Republishing our charts and statistics
The charts and statistics on The Fill Line are free to republish. Use them in an article, a report, a class, a presentation, or a post — you do not need to ask us first. We ask one thing in return: credit The Fill Line with a visible link back to the page you took the figure or chart from, and keep that link live.
Every chart has an Embed chart button with a snippet you can paste straight into a web page. Because it points at the live image, the chart you embed today keeps updating itself as new data lands — you never have to swap in a fresh screenshot. Every data page, guide, and issue has a Cite button that hands you a ready-made citation line, including the date the data runs through. If you are quoting a number, keep that date: it is what tells your reader how current the figure is.