Last week, United States Immigration and Customs Enforcement officials arrested more than 680 people in at least 12 states, shown below, stoking fears that the Trump administration is increasing the arrests and deportations of undocumented immigrants.

States where arrests occurred Wis. N.Y. Ind. Ill. Calif. Kan. Mo. Ky. N.C. S.C. Ga. Tex. States where arrests occurred Wis. N.Y. Ind. Ill. Mo. Kan. Calif. Ky. N.C. S.C. Ga. Tex. Source: United States Immigration and Customs Enforcement | By The New York Times

But a comparison of last week’s arrests and similar ones during the first four years of the Obama presidency shows that the recent level of enforcement activity is not unprecedented.

It is unclear, however, if the numbers are an actual increase in enforcement, because information on operations in only 12 states was disclosed.

In President Obama’s first year, officials arrested an average of 675 immigrants a week in so-called “community arrests.”

During the 2009 fiscal year, immigration officials made 35,094 arrests — an average of 675 each week — at individuals’ homes, workplaces or elsewhere in the community, which is similar to the number of arrests made last week.

These types of arrests are sometimes called “community arrests.” Operations on this scale do not occur every week and may take several weeks to plan.

Average number of community arrests each week 700 680 arrests last week 600 500 400 300 200 100 Fiscal year (Oct. - Sept.) ’04 ’08 ’09 ’12 BUSH OBAMA 700 680 arrests last week 600 500 400 300 200 100 Fiscal year (Oct. - Sept.) ’04 ’05 ’06 ’07 ’08 ’09 ’10 ’11 ’12 BUSH OBAMA Source: “Interior Immigration Enforcement: Criminal Alien Programs” by William A. Kandel, Congressional Research Service | Note: Includes all arrests made by national fugitive operations teams, which conducts the vast majority of community arrests. | By The New York Times

The weekly average of such arrests made by Immigration and Customs Enforcement fugitive teams under President Obama rose to 771 in 2011 and declined slightly to 719 the next year.

Data after 2012 are not readily available, but in more recent years, the number of ICE apprehensions and removals decreased overall, especially after the Obama administration began to focus on convicted criminals.

In Mr. Obama’s two terms in office, there were at least six known operations in which more than 500 people were arrested, according to an analysis by The New York Times.

Announced Number arrested April 2010 596 June 2011 More than 2,400 September 2011 2,901 April 2012 3,168 August 2013 1,660 March 2015 2,059

In one of the largest operations, the Obama administration announced in 2015 that immigration officials had arrested more than 2,000 individuals in a five-day nationwide effort that targeted unauthorized immigrants convicted of crimes. Several other large nationwide operations resulted in more than a thousand arrests.

While the numbers may not be unusual, Mr. Trump has opened the door to removing more unauthorized immigrants.

What’s different about last week’s arrests is the context, said Randy Capps, Director of Research for United States Programs at the Migration Policy Institute, a nonpartisan research group.

In 2014, the Obama administration began targeting unauthorized immigrants in three primary categories: those convicted of serious crimes, those considered national security threats and recent arrivals.

But immigrants who committed minor offenses — or none at all — were often swept up in operations. Still, by the end of Mr. Obama’s presidency, not counting migrants turned back at the border, about 90 percent of Immigration and Customs Enforcement removals from inside the United States were of convicted criminals.

President Trump’s executive order uses a broader definition of “serious crimes” and includes anyone who has crossed the border illegally — a misdemeanor.

The Obama administration was careful to say that only people who had very serious charges or were recent arrivals were priorities for enforcement, but now, everyone is a priority, Mr. Capps said.

Most of those arrested last week had criminal convictions.

Immigration officials reported that about 75 percent of the 680 people arrested during last week’s operations had criminal convictions.

Of the 161 arrested in the Los Angeles area, 94 percent had been convicted of the following crimes:

Most serious conviction Total Domestic violence 42 Drug offenses 26 Assault 23 Sex crimes 17 D.U.I. 17 Burglary 6 Weapons violations 5 Vehicle theft 4 Other 11

Of the 235 arrested in six Midwestern states, 163 had criminal convictions, 60 illegally re-entered the United States after being removed, and the remaining 12 were picked up because they had outstanding orders of removal issued by a federal immigration judge.

Not all of the 680 will be removed immediately from the United States.

Some of those arrested in last week’s operation have “final orders” to be deported and will probably be removed quickly from the country. Immigration officials can also quickly deport those individuals who re-entered the United States illegally by reinstating their previous removal order.

For others, however, immigration officials will begin a removal process, which includes scheduling a hearing before an immigration judge. In this case, individuals can get a lawyer as well as appeal the ruling, which further delays the process.