In 1951, the federal government devised a system to instantly alert the whole country in case of enemy attack. At first, the alert system was known as Conelrad. In the event of an emergency, all radio stations were to cease operation except for those able to broadcast on two designated Conelrad frequencies, 640 and 1240 on the AM dial. Emergency information would be relayed to the public on these two frequencies. The idea was that the Conelrad stations would switch on and switch off from different cities so that Russian bombers couldn’t target their signals. An indication of how seriously Conelrad was taken is that between 1953 and 1963, all AM radios manufactured in the United States were required to have triangular Conelrad markings on the dial at 640 and 1240. (Hear a bit of the first nationwide Conelrad test from 1956 here.)

Conelrad was replaced in 1963 by the Emergency Broadcast System (EBS), which made it theoretically possible for every radio station in the country to carry simultaneous emergency messages. Messages would be sent to a few designated primary stations and relayed by smaller stations monitoring them, and by smaller stations monitoring them, and so on. The Emergency Alert System (EAS), established in 1997, updated the warning mechanisms further, and marked the end of the familar EBS tests, like the one at the top of this post.

We have never learned whether any of the systems would actually work in a real emergency. I have always doubted it, as they ultimately depend on too many fallible human beings all down the line, from the White House to West Overshoe. Conelrad glitched a couple of times, in several western and southwestern states in 1955 and in northeast Wisconsin and Upper Michigan in 1959; a 1971 EBS error is more famous. Today, EAS has largely automated the process, but erroneous activations still occur.

As the old EBS script said, stations act “in voluntary cooperation with federal, state, and local authorities,” sort of. Stations are required to activate for federal-level alerts, but not state or local ones. (In Dubuque 35 years ago, we fired EBS tones for tornado warnings, but no other station I ever worked for did it.) Controversially, EAS wasn’t activated locally in New York on 9/11, even though those attacks were surely the kind of thing for which it was invented. In many states today, the decision to broadcast an alert is made by local emergency management officials or the National Weather Service, in recognition of the fact that many radio and TV stations operate unstaffed some of the time.

Once all of us started carrying personal communication devices, it made sense to start using them for such alerts. The Wireless Emergency Alert (WEA) system has already buzzed you, probably—if you’ve ever gotten an Amber Alert on your phone, for example. It is possible to use the settings on your phone to opt out of such alerts, but there’s one setting you can’t change: the presidential alert. That’s why Conelrad and all the rest were invented, after all: for the president to communicate with Americans before, during, and after the dropping of the Big One. And it’s still a main purpose of EAS and WEA today, made official by federal laws passed in 2006, 2008, and 2015 that modernized the alert system for the cell-phone age.

A national EAS test was performed in 2016, and at that time, a lot of right-wingers lost their minds, screeching that it meant President Obama was going to take over the nation’s airwaves for propaganda purposes. (A 2017 test happened practically without anyone noticing, however.) Another national EAS test was scheduled for tomorrow, although it’s now been postponed to October 3. It is the first such test to incorporate the un-opt-out-able presidential alert on cell phones. Now it’s the left wing’s turn to freak out, imagining that Donald Trump will start using the system the same way he uses Twitter.

I don’t doubt that Trump would look fondly at a system that could allow him to force his opinions on people who might otherwise manage to ignore him. But sending a presidential alert is not something any president can do unilaterally. This is due in part to the 2015 act, which codified anti-Obama paranoia into law by limiting the president’s authority to activate emergency systems. The message we’ll all receive on October 3 will be a text, labeled as a presidential alert with some boilerplate script, most likely with no direct participation from Trump at all.

(Thanks to longtime friend of the blog Dan Kelley at the Michigan Association of Broadcasters for his EAS expertise.)