Moving Day was a tradition in New York City dating back to colonial times and lasting until after World War II. On February 1, sometimes known as "Rent Day", landlords would give notice to their tenants what the new rent would be after the end of the quarter, and the tenants would spend good-weather days in the early spring searching for new houses and the best deals. On May 1, all oral leases (the majority of tenants) in the city expired simultaneously at 9:00 am, causing thousands of people to change their residences, all at the same time.

The tradition was likely derived from the practice of verhuisdag [nl], with contracts in the Netherlands generally ending on May 1, while The Encyclopedia of New York City links it instead to the English celebration of May Day. Washington Irving's satirical 1809 novel A History of New York gives an origin myth centering on a movement on that date of early Dutch colonists on the Communipaw Ferry route across the Hudson from New Jersey, while later fanciful writers such as Arthur Guiterman ascribe it as the date of the first crossing across the Atlantic from the Netherlands. While it may have originated as a custom, the tradition took force of law by an 1820 act of the New York State Legislature, which mandated that if no other date was specified, all housing contracts were valid to the first of May – unless the day fell on a Sunday, in which case the deadline was May 2.

In 1799, an observer commented that New Yorkers "are seized on the first of May, by a sort of madness, that will not let them rest till they have changed their dwelling." Because there were not enough cartmen to handle all the traffic, farmers would come from Long Island and New Jersey to rent out their wagons at high prices. By 1820, because of the large increase in the number of propertyless renters, Moving Day had become "pandemonium", with the streets gridlocked with wagons carting household goods. The tradition was still in force in 1848, when the Tenant League denounced it as a way for landlords to raise rents every year. The cost of moving was another concern, as cartmen sometimes charged more than the official rates set by city ordinances – people were known to pay up to a week's wages to be moved – and the truckman might, if the customer refused to pay on delivery, take their belongings to Police Headquarters, charging for the additional transportation.

By 1856, some erosion of the strict adherence to the custom of Moving Day was noted, as some people moved a few days before or after the traditional day, creating, in effect, a "moving week". Once the economic depression of 1873 was over, more housing was constructed, dropping the price of housing down, and subsequently people had less need to move as often.

Near the end of the 19th century, many people began leaving the city for the cooler suburbs in the heat of summertime, and as a result October 1 became a second Moving Day, as people returning to the city would take their belongings out of storage and move into their newly rented homes. The October date may be related to the English custom of paying land rents on Michaelmas, which falls on September 29. Eventually, the October date began to supplant the traditional May date, so that by 1922 the Van Owners Association reported only a "moderate flurry" of activity on the Spring day. The movers also attempted to get legislation passed to spread out the Fall rush to three dates: the firsts of September, October and November. Over time, the tradition of a specific Moving Day began to fade, with the remnant evident in commercial leases, which still generally run out on May 1 or October 1.

At the height of Moving Day in the early 20th century, it was estimated that a million people in the city all changed their residences at the same time. Resistance to Moving Day was strong in the 1920s and 1930s, while it still made cultural appearances as in the 1926 Broadway song "Mountain Greenery", but it took the start of World War II to end the general practice, as the moving industry found it difficult to find able-bodied men to do the work. The post-war housing shortage and the advent of rent control finally put an end to the custom for good. By 1945, a newspaper headline announced "Housing Shortage Erases Moving Day."

The basis for Moving Day within NYC was from English common law that had remained present within NYC, and other American cities. It existed as a form of tenant protection from at will eviction, for those without a written lease. The vast majority of tenants at the time depended on oral leases, a practice that existed under common law that had the same legal status as written leases.

Importantly, an old legal statute reenacted in 1896, stated that leases of unspecified duration would expire on May 1 annually. Effectively making any oral lease a year long. For this reason, a tenant could legally challenge a landlord who asked for a rent increase on October 1 on the grounds they had oral agreements that fixed the price of the rent until April 30.