ON TUESDAY, I TRIED to make it a point to stand at least three feet from the person in front of me at the Cambridge post office. The Centers for Disease Control and Prevention recommendation on “social distancing,” or the space between you and another, is that you stay be about six feet apart.

While social distancing was relatively under control there, the same was not true outside Boston’s downtown Registry of Motor Vehicles office. NBC10Boston tweeted out a bird’s-eye view of the line, showing people far less than six feet apart, and in some cases only separated by inches.

The state had extended expiration dates for licenses, and suspended road tests, but some things, like getting a car registered and obtaining license plates, still require people to go in to one of eight registry locations that have reopened. Only 25 people are allowed inside at a time in compliance with Gov. Charlie Baker’s social distancing order.

“We will be limiting the number of people allowed inside Service Centers and once those limits are reached, customers will have to either leave and come back or wait outside until it is possible to let them in while still maintaining social distancing,” said Transportation Secretary Stephanie Pollack in a statement to the Boston Herald.

Hand sanitizer and disinfectant wipes were being doled out inside, but not to the people outside who waited to up to three hours. There was also no enforcement of social distancing outside, and people did not seem apt to initiate it themselves.

Some people don’t have a choice over breaking the six-foot guideline. Grocery store employees often stand less than two feet from customers when they’re checking them out. They usually don’t have gloves or masks available. Because coronavirus is airborne — spread through respiratory droplets on surfaces and in the air — this is cause for concern. Trader Joe’s workers are attempting to get hazard pay and extended sick time in the event that they get infected. It’s rare to see any enforcement of social distancing at check-out lines.

It’s easier to tell people to stay home, even to mandate it in most circumstances, as a way to impose isolation than to count on steadfast observance of the six-foot rule. The repercussions for not even trying can be overwhelming.

Business Insider writes that in countries like China and Italy, where people were not isolated early enough in the pandemic, “the number of infected people seemed to skyrocket overnight. The reason for this is the virus’s exponential growth trajectory.” Studies suggest that without measures to curtain its spread, on average, each person with the virus infects 2.5 other people — making coronavirus far more contagious than the seasonal flu.

With more than 8,700 known coronavirus cases in the US (researchers suggest that number is far higher) and more than 100 deaths, public health experts are urging isolation to “flatten the curve” of the outbreak. That means slowing the virus’s spread so that the country’s hospitals aren’t overwhelmed.

The Washington Post has created simulations on what flattening the curve can do, showing how infection can spread without social distancing, and how it can be slowed with the right behavior changes.

Baker has recommended social distancing at every press conference, but much of this still remains at the discretion of individuals.

With restaurants only allowed to operate on a take-out basis and bars shuttered, a main concern now is how to get the people at grocery stores or who are outside properly distanced. Requiring grocery stores to limit how many people go inside at once while asking people in lines to remain far apart could be one of those solution.

A simple wet cough from the person a foot away from you can go a long way. A study published in the New England Journal of Medicine on Tuesday found that the virus could be detected up to three hours later in the air, up to 24 hours on cardboard, and up to two to three days on plastic and stainless steel.

Continued public education about the imperative of social distancing seems crucial.

Back at the post office, the person behind me was standing less than a foot from me when I asked her politely to please back up a little — “social distancing is important,” I said. She rolled her eyes, smiled, and obliged.