Migrants attempting to cross the U.S.-Mexico border are surging, but recent data finds the largest increase is in southwestern Arizona.

According to U.S. Customs and Border Protection, immigration authorities were involved with 149,110 migrant encounters in the Yuma Sector during the first six months of fiscal year 2022. Data released this week shows that is a 589% increase from the first half of the previous fiscal year.

Arizona has two set Customs and Border Protection divisions, Yuma and Tucson. During the same first fiscal year 2022 (October 2021-March 2022), the Tucson Sector officials reported 122,619 migrant encounters, which is up 52.9% from the same period a year earlier.

Del Rio, Texas, was the only other reported border protection sector that saw a triple-digit increase, at 184.5%.

Of the nine Customs and Border Protection Southwest border divisions across California, Arizona, New Mexico and Texas, more than 1 million migrant encounters over the last sixth months were reported, which is an 83.8% year-over-year increase.

The border towns are expecting to see a surge of crossers if the Biden administration goes through with a plan to lift a pandemic-era Title 42 order denies migrants a chance to seek asylum to mitigate the spread of COVID-19. It has been into effect since the Trump administration in March 2020.

With COVID-19 cases declining, the Biden administration recently announced intentions to end the policy on May 23.

Human rights groups and migrant supporters have called for the lifting of the public health order saying the U.S. has a legal obligation to allow people to seek asylum.

However, some Democrats in Congress, including Arizona Sens. Mark Kelly and Kyrsten Sinema, are working to encourage Biden to keep Title 42 in place until there’s a formal plan in place to handle the predicted surge of asylum seekers.