“Crews respond to early morning explosion at a Mississippi chemical plant”
Read at Gulf NewsReported by one source so far. It is confirmed when a second, independent source reports the same thing.
The shading behind a date drains as it ages: full when new, three quarters at 1 hour, half at 6 hours, a quarter at 12 hours, empty after a day. The date is when the source published it.
The line under a story shows when it was reported. Now is at the end. The shaded part runs from its first article to its latest; each mark is an article, taller where several came out within 15 minutes. In lists the line is the last two days, so stories compare; a faded start means the story began earlier. On a story page it runs from the first article to now.