Among the reasons for making a border crossing between ports of entry is the “metering” policy that has restricted official points of entry.
The following article shows that the numbers processed officially has been relatively constant, resulting in increased numbers waiting on other sides of the border.
As part of a new 'metering' policy, US officials are turning asylum seekers away at ports of entry along the southern border. Thousands wait, straining the resources of Mexican border towns.
Meanwhile Cubans have been added to those who get sent back to Mexico
The United States is more than doubling the number of asylum seekers it returns to Mexico in one city and adding groups like Cubans as it rapidly expands a policy to make migrants wait out claims south of the border, Mexican and U.S. officials said.