WASHINGTON—The number of immigrants crossing the border illegally into the U.S. appears to be on the rise again after dropping during the recession.

The total number of immigrants living in this country unlawfully edged up from 11.3 million in 2009 to 11.7 million last year, with those from countries other than Mexico at an apparent all-time high, according to a report released Monday by the Pew Research Center’s Hispanic Trends Project.

The change is within the margin of error, and there will be a more precise census measure released later this year. Still, based in part on other factors such as increased U.S. border apprehensions, the sharp decline in illegal immigration from 2007-2009 has clearly bottomed out, with signs the numbers are now rising, Pew said.

Pew said that among the six states with the largest numbers of immigrants hereillegally, only Texas had a consistent increase in illegal immigration from 2007 to 2011, due in part to its stronger economy. Its number was unchanged from 2011 to 2012. Two states — Florida and New Jersey — had an initial drop but then increases during the same 2007-2011 period. Three states — California, Illinois and New York — showed only declines.

“As a whole, with the recession ending, the decrease in illegal immigration has stopped,” said Jeffrey Passel, a senior demographer at Pew.

Passel noted that historically the level of illegal immigration has been closely tied to the strength of the U.S. economy and availability of jobs. Since 2009, the average U.S. unemployment rate has dropped from 9.3 percent to 8.1 percent last year, with signs of strength in the construction industry, which yields jobs generally attractive to newly arrived Latino immigrants.

The Pew analysis is based on census data through March 2012. Because the Census Bureau does not ask people about their immigration status, the estimate onillegal immigrants is derived largely by subtracting the estimated legal immigrantpopulation from the total foreign-born population. It is a method that has been used by the government and Pew for many years and is generally accepted.

Analysts said it was hard to predict whether immigrants in the country illegally could eventually exceed the record total of 12.2 million in 2007. Continued modest increases are possible, but another big surge like the one seen in the late 1990s and early 2000s isn’t likely, due in part to demographic factors such as Mexico’s aging workforce.

“Labor demand in the U.S. is still slack and wages are eroding, whereas there are jobs in Mexico and wages are slowly rising as labor force growth there decelerates,” said Douglas Massey, a professor of sociology and public affairs at Princeton University who is co-director of the Mexican Migration Project. “The pressures for mass migration are diminishing for now, but who knows what kind of disasters lie ahead?”

Analyses of census data from the U.S. and Mexican governments show that the number of immigrants here illegally peaked at 12.2 million in 2007, during the U.S. housing boom, and before the recession hit. It then dropped roughly 7 percent to 11.3 million in 2009, the first two-year decline in two decades, due to the weak U.S. economy which shrank construction and service-sector jobs. Much of the decline came as many Mexican workers who already were here saw diminishing job opportunities and returned home.

Since then, the U.S. economy has shown some improvement, while public opinion regarding immigrants has shifted in some cases in favor of granting legal rights. For instance, some state legislatures this year have passed immigrant-friendly measures such as college tuition breaks and rights to driver’s licenses, even as others enacted laws aimed at tightening the system.

A look at some immigration details, by the numbers:

—In all, the number of Mexicans here illegally stood at roughly 6 million last year, down from the 2007 peak of 6.9 million and largely unchanged since 2010. Mexicans now make up 52 percent of immigrants in the U.S. illegally, down from 57 percent in 2007.

—The level of illegal immigration from countries other than Mexico rose to a record 5.65 million, higher than the 5 million in 2009 and apparently surpassing the 2007 peak of 5.25 million. The record number in 2012 is a preliminary determination because of margins of error in the surveys.

—In past surveys, non-Mexican immigrants here illegally have come primarily from Central America, at roughly 15 percent; followed by South America, the Caribbean and other parts of Latin America at 12 percent; and Asia, at roughly 10 percent. The Obama administration has recently said that unrest and poverty in many Central American nations are a large factor behind illegal immigration into the U.S.

—Separately, U.S. Border Patrol data show a modest increase in the number of apprehensions at the Mexican border from 2011 to 2012, increasing to 365,000. That was because of growing apprehensions of non-Mexicans, as opposed to Mexicans, which declined. Historically, increases in border apprehensions have tended to coincide with increases in illegal immigration.

—In particular, analysts have said that immigrants are shifting their migration paths from Arizona to deep southern Texas, due in part to that state’s stronger economy, as well as increases in Central American immigrants who seek a more direct route to the U.S. Agents from the Border Patrol in Texas’ Rio Grande Valley have apprehended nearly 150,000 so far this fiscal year, a 58 percent increase over 2012. About 94,000 of those border crossers arrested have been from countries other than Mexico.

The latest numbers on illegal immigration come as prospects for passage of a comprehensive U.S. immigration bill appear dim. A bill passed by the Democratic-controlled Senate and backed by the White House includes billions for border security as well as a 13-year path to citizenship for the 11 million immigrants already hereillegally.

But most House Republicans have rejected this comprehensive approach, and the House Judiciary Committee has moved forward with individual, single-issue immigrationbills that could come to the floor sometime later this year or next. It’s unclear whether the GOP-dominated House will ever pass legislation that could form the basis for a final deal with the Democratic-controlled Senate.

Steve A. Camarota, director of research at the Center for Immigration Studies, a Washington group that advocates tighter immigration policies, said the immigrationissue will be tough to resolve.

“The numbers remind us the problem of illegal immigration isn’t going away anytime soon,” he said, “unless we take steps to enforce the laws or have legalization of those here illegally.”