When a bus packed with migrants pulled into downtown Los Angeles in mid-June, it caused a local stir: In a city with one of the country’s largest immigrant populations, this was the first busload to arrive courtesy of the Texas governor, Greg Abbott.

This week, the 12th such bus arrived in Los Angeles, part of the Texas governor’s determination to share the responsibility of caring for newly arrived migrants with Democratic politicians who have supported a more welcoming national immigration policy.

Both the Texas governor and Gov. Ron DeSantis of Florida have offered migrants free rides from border towns to New York, Chicago, Philadelphia and several other cities since last year. The arrivals have overwhelmed the resources of some cities, straining shelters and aid resources.

“It is abhorrent that an American elected official is using human beings as pawns in his cheap political games,” Mayor Karen Bass of Los Angeles said of the busing program in June.

But the reality is that the number of migrants offered free passage from Texas over the past year is a fraction of those who regularly make their way from the southern border to cities around the country — to places where there are jobs, family connections and networks of other immigrants from their homelands. And it has been that way for years.

Of the roughly 11 million undocumented immigrants now living in all 50 states, according to demographers’ estimates, most began their new lives with a trip from a border city or airport — usually paid for by a relative, an aid group or their own savings, not the Texas governor.

What was Abbott’s plan?

Intent on highlighting the large number of people crossing the border in recent years, which he blames on the Biden administration’s immigration policies, Mr. Abbott devised a plan to approach migrants after they had been processed by the border authorities and offer them free rides on chartered buses.

“I’m going to take the border to President Biden,” he said at a news conference after introducing his plan in April 2022.

Many migrants have been grateful for the free transportation, because they often have little money left by the time they complete a monthslong trek to the U.S.-Mexico border.

Lever Alejos, a Venezuelan delivered to Washington, D.C., last July, said, “I feel fortunate the governor put me on a bus to Washington.” He has found work and started sending money and gifts to his young son back home. He recently bought a car.

Does everyone ride the buses?

No. In fact, the migrants boarding the Texas-funded buses represent only a fraction of the thousands arriving at the border each month, and some migrants are wary of accepting a free ride.

The Texas busing program has sent about 34,740 migrants to other states since April of 2022, enough to populate a small city. But that is a paltry subset of the hundreds of thousands who have crossed the border during that period, most of whom have probably also made their way to destinations outside Texas.

New York alone has received more than 100,000 migrants in the last year; only 13,100 were sent on buses provided by the state of Texas.

What’s more, many migrants are crossing the border every day in Arizona, California, New Mexico and even parts of Texas where no free bus service is available. After being released by the border authorities, they typically arrange travel on their own to their U.S. destinations.

Thousands of immigrants a year take Greyhound buses from Tucson, San Diego and San Antonio, and some of them take commercial flights, which they can board as long as they have identification. They pay for the transportation themselves, or relatives or friends already in the country buy tickets for them. In some cases, charity groups or volunteers offer money or mile vouchers for migrant travel.

Then why is there such a sudden strain on resources in some cities?

Migrants arriving on the free buses tend to be needier than others. That reflects a change in the composition of migrants who have been crossing the border over the past two years. A large share of those riding the Texas buses are Venezuelans fleeing economic hardship and political turmoil.

In contrast to Mexicans and Central Americans, who have been migrating to the United States for decades, Venezuelans are unlikely to have friends and family members to receive them because their wave of migration is a new phenomenon.

With no money and no family, Venezuelans have overwhelmed nonprofit organizations and volunteer groups since spring last year. Because they have no connections in the United States, Venezuelans are also more likely to want to travel to a big city, like New York, where they expect to find jobs and assistance.

Venezuelans comprise the majority of migrants staying in homeless shelters in New York. They continue to arrive, although numbers have dropped in recent months.

The large numbers of Haitians arriving recently have also proved taxing for some cities, because many of them also arrive with few resources of their own.

New York City and Massachusetts are especially strained by the influx of migrants because they have right-to-shelter laws requiring the provision of shelter to people who request it, although in Massachusetts, it applies only to families with children, and to pregnant women.

Why are some migrants remaining in homeless shelters for months?

Most migrants who cross the border are seeking asylum in the United States, but they are not eligible to apply for work permits until about six months after they have filed petitions requesting protection. The large number of applications has also created a backlog.

Without employment authorization, it is difficult to secure work. Some migrants find jobs in the informal economy or are paid cash to do blue-collar work. But even then, it takes time for them to save enough money to rent a place, and landlords often require proof of income and other documentation that they do not have.

What other assistance do the migrants receive?

Families can receive food, medical care and other assistance, depending on the state. Children, regardless of immigration status, are entitled to enroll in public schools everywhere.

For New York alone, the cost of assisting the migrants is in the billions of dollars. The financial burden imposed by the newcomers has prompted leaders in New York, Illinois and Massachusetts to declare states of emergency, urging the federal government to provide resources.