Before post offices existed, most people had two options for delivering a letter. Someone with money to spend (or a particularly important message) could hire a courier for hand-delivery. In the era before trains, planes and automobiles, this could mean days spent on horseback riding from one state to another, with prices that reflected the intensive labor involved in delivering the mail.

Alternatively, many people used the local inn as a way to send mail. They would toss their letters on a table in the room, address included, for travelers headed in that direction to grab and drop off at an inn when they arrived. As you might imagine, this informal system was not reliable.

In 1775, the Second Continental Congress appointed Benjamin Franklin as the nation's first postmaster general, charged with oversee a mail-delivery organization that would eventually become the United States Postal Service, or USPS.

This was not an accident or the fluke of a great man who got bored. The postal service links the United States together. It ensures that every man, woman and child has access to cheap, reliable communication everywhere in the country. It allows citizens to speak with their government and their government to get in touch with them. The government could have restricted access to the USPS for official business; certainly that would have been cheaper and easier. Instead, the USPS serves everyone, with letter carriers dedicated to delivering greeting cards as reliably as they do audits.

The founders believed that this was so important that postal service is one of the few government agencies specifically called for in the Constitution. Article One, Section Eight charges Congress with the power "to establish Post Offices and Post Roads," and since 1775 and the Second Continental Congress, it has.

How Many People Does The Post Office Employ?

The United State Postal Service USPS runs one of the largest organizations in the country. It has the second most civilian employees with 634,447 career and non-career employees. It its the third largest employer, government or private, in the country, behind the armed forces and Walmart (WMT) - Get Report . (No other employer comes even close to Walmart's 2.2 million employees.)

According to the postal service's own data, the USPS pays out $1.9 billion in salaries and benefits every two weeks to its staff, who, in turn, handle a whopping 47% of the world's mail. This includes an enormous amount of mail we ordinarily think of as delivered by private companies such as UPS (UPS) - Get Report , Federal Express (FDX) - Get Report and Amazon (AMZN) - Get Report . It is very common for private shipping companies to rely on the postal service to transport packages over long distances, then take over for last-mile distribution services.

In 2018, postal service employees traveled a collective 1.4 billion miles to deliver their letters, with the USPS spending $70.6 billion in operating revenue to do it.

And while we're on the subject of facts and figures, the USPS delivers more than 146 billion pieces of mail every year.

How Much Do Mail Carriers Make?

To move that kind of volume, the postal service needs an army of mail carriers, and we don't use that term lightly. The USPS employs 342,410 people to deliver letters. (This data is from the most recent collection in 2018.) More than half of the postal service's staff is dedicated just to the physical delivery process, a group almost as large as the standing army of Turkey.

The rest of the postal service's staff members work in a wide range of fields, including customer service, mail sorting, maintenance and repair, infrastructure and data, and all of the many jobs a large organization needs to sustain daily operations.

Income for mail carriers is fairly consistent across the country, showing less variation compared to costs of living than many other professions.

As of the most recent available data, a mail carrier earns the following:

• Average Hourly Wage: $24.89

• Average Annual Income: $51,780

• Median Wage: $26.54

• Median Annual Income: $55,210

Mail carriers receive raises based on seniority, leading to higher pay over time. In addition, because they are paid by the hour, overtime can significantly affect a mail carrier's income. In particularly busy markets (such as large cities), an individual can earn more by taking additional hours when available.

These factors lead to a wide range of pay scales. At the lowest, the bottom 10 percent of mail carriers earn approximately $17.78 per hour, or $36,990 per year. At the highest, the top 10 percent of mail carriers earn approximately $30.75 per hour, or $63,970 per year.

The cost of living locally can also impact a mail carrier's salary to a limited degree. The annual mean wage for this profession in highly inexpensive states is approximately $50,000, while the annual mean wage in expensive states ranges from $51,890 to $57,330.

Where Does The Money Come From?

As many Americans have learned during the government shutdowns of the past decade, the USPS does not actually rely on the coffers of the federal government for its money.

Despite operating as an essential government agency, one relied upon by services like the IRS, local election boards and the military, the postal service is entirely self-funded. This means it takes no revenue directly from taxpayer dollars. Instead, it collects all of its money from business operations. Its biggest money makers are first class mail (from which brought in $24.9 billion in 2018) and shipping packages, (from which it earned $21.5 billion in 2018).

Marketing mail makes up the third tent pole of USPS revenues with $16.5 billion in 2018.

Competition from multiple sources has caused the postal service to struggle financially, but arguably the most important change has been e-mail and other forms of digital documentation. This has increasingly undercut the agency's first class mail operations, its largest source of revenue, causing the USPS to lose more and more money each year. Internet commerce hasn't been all bad, and in some ways has helped the postal service enormously, with the rise in shipping fees partially offsetting losses in first class mail. But it hasn't been enough to stem the red ink.

It's not that the postal service has a revenue problem - far from it. The USPS took in more than $70 billion in revenue in 2018. However, the USPS that same year spent more than $74 billion in operating expenses, resulting in a net loss of $3.9 billion. The problem? The postal service's expenses are not elastic. Unlike a private company, the USPS effectively operates as a government agency and can't simply cut unprofitable routes or charge triple for remote locations.

Why We Keep The Post Office

Despite some snarky hot-takes, keeping the postal service has nothing to do with nostalgia.

One of the core functions of government is to set the minimum standards for society. In a free-market economy like the United States, citizens don't always expect the government to create ambitious or far-reaching services. Instead they expect government will create the baseline of services necessary for modern life. The postal service exists to ensure all Americans have access to a cheap, reliable form of communication.

The postal service delivers this service without favor or prejudice. Anyone can send a letter through the U.S. mail, and they can send it to any address in the country (or, often, out of it). Most importantly, a mail carrier will deliver that letter even when it is unprofitable to do so.

This is the core of the financial problem the USPS faces, and it is why this agency is so critical.

In an age of Federal Express, Amazon Prime, drone delivery and e-mail, private services seem to have effectively made old-fashioned mail obsolete. They can deliver a message or parcel faster and seemingly with better customer service than a U.S. postal worker.

But any private company can shut down, change its services, or discover that its business model isn't as strong as everybody thought. (Just ask the cities which have steadily gutted their public transit systems in favor of Uber, only to face serious questions about the sustainability of the ride-share business model.) Working for a profit means working only when it makes a profit. A private delivery service won't carry a package unless it makes financial sense. It will cut unprofitable routes and charge extra on expensive ones.

The USPS does none of those things. The postal service delivers to everyone for the same stamp whether you live downtown or 100 miles out. (It does charge extra to go from one part of the country to another, but the price is the same within a region.) It makes those deliveries even when it loses money. It guarantees that no one in the United States will ever get cut off or left on their own.

That's why there is still a postal service.