What this shows
The Lower-48 power grid is not one machine — it is three interconnections and more than sixty balancing authorities, each seeing only its own territory. EIA's Form 930 collects hourly demand from every one of them and rolls it up, which makes this the only place total US electricity demand exists as a single number. This page plots that number for the last two days, alongside the day-ahead forecast the reporting authorities themselves filed.
How to read the curve
National demand has a double structure: a daily wave that troughs before dawn and peaks in the evening, and a huge seasonal swing between mild-weather days near 450 GW and summer heat waves above 700 GW. Because the country spans four time zones, the national peak is flatter and later than any one region's — the East is ramping down as the West is still climbing.
What the forecast line is — and is not
The dashed line is EIA's day-ahead demand forecast roll-up. Not every balancing authority files one, so it covers a reporting subset and reads below total demand — useful for the shape of tomorrow, not as a like-for-like prediction of the settled line. That coverage gap is also why this page publishes no accuracy scorecard: scoring a subset against the whole would manufacture a miss that is really a definition difference.
Where the demand is
The regional breakdown below splits the same hours across EIA's thirteen aggregation regions. The Mid-Atlantic, Southeast, Texas, and Midwest carry the biggest blocks; California and New York are smaller in megawatts than their economies suggest because of milder climates and efficiency. Every Lower-48 balancing authority rolls up into exactly one region, so the parts genuinely sum to the whole.
How current it is
EIA collects the data hourly from each balancing authority, so the demand curve trails real time by an hour or two and recent hours are routinely revised as authorities re-file. The by-fuel generation series lags further — several hours — which is why the fuel section names the exact hour it describes.