The charts on AllPollsUSA.com show how each party's or candidate's vote share has moved over time. The vertical axis shows the share of the vote. On timeline charts the horizontal axis is the date; on comparison charts it is the number of days to election day, counting down from 91 to 0, so the final stretch of several campaigns can be seen side by side — older elections are shown more faded (transparent) than the most recent one. Where available, the official election result is shown at the far right.
The charts are interactive:
- Zooming in: on timeline charts you can zoom in: use the slider (dataZoom) below the chart, scroll with the mouse wheel over the chart, or drag to shift the visible window. Comparison charts have no zoom; their range is fixed.
- Viewing values: move your mouse over the chart (hover) to see a vertical guide line with a tooltip listing every polling firm at that point, with its exact value. Individual polls show whole percentage points; where the line is drawn between two polls, the interpolated value is shown with one decimal, e.g. 2.3.
- Showing or hiding polling firms: click a name in the legend to temporarily show or hide that firm in the chart. When many firms or parties are shown at once, you can scroll through the legend.
- Names next to the line: with twenty or fewer firms or parties in one chart, the name is shown directly at the right-hand end of each line, so you can identify a firm without the legend.
- Records: a pin marks the highest or lowest figure a party or candidate has ever reached, or within a given period (for example the last 5 or 10 years). When viewing a single firm's chart, the tooltip notes "according to {pollster}" — such a record only applies to that firm, not the all-firm average.
- Downloading: click the camera icon in the top-right of the chart to download it as an image (PNG).
Two different series are charted on this site. The home page shows the generic congressional ballot — a single Democratic-versus-Republican question asked all year round, in and out of election years. The presidential page shows the head-to-head between the nominees of one presidential cycle at a time. They answer different questions and are never combined in one chart.
The presidential chart has long empty stretches, and that is real rather than missing data: a cycle's head-to-head polling only begins once both nominees are settled, so there is little to nothing to show between one election and the next nomination. One candidate's line ending and another's beginning in the middle of a cycle means exactly what it looks like — the nominee changed.
If a polling firm hasn't published for a long time — for example because it paused fieldwork for a period — that firm's line is broken rather than stretched to the next available point, so the chart doesn't give a distorted impression.
Below every chart is a table with the same figures in text form: useful as an alternative overview, and as a fallback when the interactive chart itself can't load.