If you fly three or four times a year and don’t have Global Entry, you’re crazy.

I know that’s a bold statement—and I have no way of actually judging your mental capacities—but give me a moment to explain why it’s an essential tool for any traveler, even those staying within the country.

Global Entry is a Customs and Border Protection program that, after a background check, allows travelers to skip lines at immigration and customs, using a kiosk to quickly reenter the country. The online application process takes a bit of time, and a subsequent in-person interview is required.

Once complete, though, you’ll not only laugh at long immigration lines but also race through airport security. That’s because the TSA considers Global Entry members “trusted travelers” and automatically includes them in the affiliated PreCheck program. And entry into that program is priceless.

Here’s why: at airport security checkpoints, you get to use a special line, leave your shoes, belt, and jacket on, keep liquids and laptops in your bags, and use a standard metal detector, not the full-body scanners.

I routinely make it through security in less than two minutes thanks to PreCheck. Let me repeat that: it typically takes me less than two minutes to clear airport security.

The TSA can ask you to go through additional screenings; on one of my trips out of New York last year, I was randomly selected to have my hands swabbed to test for explosives. It added less than a minute to my checkpoint experience, and I haven’t been selected again since.

The program initially opened up at a handful of the country’s largest airports but has been expanded to 102 with more lanes and airports coming online throughout 2014. The TSA tells me it hopes to eventually have PreCheck at 350 airports. That’s practically everywhere you would ever want to fly. There are only 450 or so airports in the country with commercial flights requiring TSA checkpoints.

Now a bit of a warning: not every checkpoint at every airport has a PreCheck lane. And at off-peak hours, the PreCheck lane might be closed. Check the TSA site for which airports have PreCheck and where those lanes are.

Right now, the airlines participating in the program are: Alaska Airlines, American Airlines, Delta Air Lines, Hawaiian Airlines, JetBlue Airways, Southwest Airlines, United Airlines, US Airways, and Virgin America.

Speeding people through PreCheck allows the TSA to dedicate more staff to other passengers, ideally reducing lines for them too. (This is also why the TSA is now letting children 12 and under and adults 75 and over keep their shoes on.)

The TSA says that 25 percent of the 1.8 million passengers who pass through airport security checkpoints daily are now using some form of expedited screening. Right now about 25 million people have experienced PreCheck (if you’ve used it 40 times, you count 40 times in the statistic)—a pretty small number considering that there are about 740 million passenger trips a year in this country.

Having more airports participate should drive that percentage up. The TSA is also trying to get more people to sign up.

I suggest that people enroll through Global Entry. (Here’s the online enrollment form.) It costs $100 and is good for five years. I hope that they will eventually let people renew for free, but given our government’s financial issues, I highly doubt that.

There are a couple ways to waive the fee. American Express refunds the $100 for holders of its platinum card who use that card when applying. And United gives its Global Services, Premier 1K, and Premier Platinum elite frequent fliers a code to use at enrollment. (More information on United’s program can be found here.)

The TSA is also rolling out a separate $85 program just to join PreCheck. Personally, I would rather spend the extra $15 to get to also cut the lines at immigration and customs. But if you don’t have a passport, that program will at least allow you to participate. Members of the government’s Nexus and Sentri programs are also automatically eligible for PreCheck.

Once you are approved for one of these programs, there is one final important step. Take your new known traveler ID number—it’s on the top left corner of the back of your Global Entry card—and enter it in your frequent-flier profiles for each airline. (Look for the spot near where you enter your date of birth and gender.) This is the only way airlines can generate a boarding pass with the PreCheck designation on it.

I should note there are two other ways to get PreCheck. The first is being a top-tier elite flier with an airline and opting in to the system online. However, you aren’t guaranteed to always be able to participate. And if you happen to be on an airline where you don’t have status, you can’t use it. If you fly enough to have status, you should spend the $100 for Global Entry.

The TSA is also randomly giving other passengers the PreCheck designation on a flight-by-flight basis. For the overall public, that should speed up the process.

For road warriors like you and me…well, I just hope this doesn’t clog up the speedy PreCheck lines we’ve come to love.

Scott Mayerowitz is an airlines reporter for the Associated Press. Read his stories on the AP site and follow him on Twitter @GlobeTrotScott.