A live flight tracker reveals the impressive impact on New Zealand's travel restrictions compared to the United States of America (US).

Nanotechnologist Dr Michelle Dickinson, also known as Nanogirl, shared a surreal tweet comparing flights operating in New Zealand to the US.

"New Zealand early lockdown has to be one of the best in the world. Was just looking for flights & found 1 cargo plane," she wrote.

"Then thought I'd look at what the plane travel situation looked like for the country with the highest number of confirmed #COVID-19 cases in the world the USA."

The US currently has at least 139,745 cases, 2448 deaths with 4435 recovered from the illness.

New Zealand early lockdown has to be one of the best in the world. Was just looking for flights & found 1 cargo plane. Then thought I’d look at what the plane travel situation looked like for the country with the highest number of confirmed #COVID-19 cases in the world the USA 😳 pic.twitter.com/MygUFjVcQU

— Dr Michelle Dickinson (@medickinson) March 29, 2020

Meanwhile, New Zealand has much lower statistics - including 476 cases, 38 probable cases, 1 death and 56 recovered.

At 11.59pm on Thursday, New Zealand went into lockdown and the country's borders closed to almost all travellers - not including New Zealand residents.

Some exceptions include: humanitarian reasons, health and other essential workers
citizens of Samoa and Tonga for essential travel to New Zealand, the holder of a visitor visa who is the partner or dependent of a temporary work or student visa holder, and who normally lives in New Zealand and is currently in New Zealand.

No other foreign traveller can now enter New Zealand.

Regional flights are allowed for those who have returned from international travel in Auckland and need to make their way home to their region.

Meanwhile in the US, according to the CDC only foreigners from a certain number of countries are banned from entering, including:

• China
• Iran
• European Schengen Area (Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, Monaco, San Marino, Vatican City)
• United Kingdom (England, Scotland, Wales, Northern Ireland)
• Republic of Ireland

Covid19.govt.nz: The Government's official Covid-19 advisory website

Flight Radar showed that at least 17 flights were operating in New Zealand. Photo / Flight Radar

Currently, regional flights are still allowed in America, which implicate one of the fundamental premises of the union among the 50 states: the right of American citizens to travel among them freely.

Today at 10.48am, Flight Radar showed that at least 1500 flights were operating in the US, while New Zealand had at least 17.

The CDC, who do not generally issue advisories or restrictions for travel within the US, urged citizens to consider taking precautions including checking if there are Covid-19 cases in the area they are travelling to.

New York remained the hardest hit, with more than 52,000 confirmed cases and at least 728 deaths.

President Donald Trump's day-long dance over whether he would order a federal quarantine of the New York City metro region ended with him ultimately retracting the idea.