Roughly 400 mainly Central American migrants blocked the Gateway International Bridge, which spans the Rio Grande River between Matamoros, Mexico, and Brownsville, Texas, on Thursday. The men, women and children say they are frustrated by the delays and uncertainty they face in awaiting asylum processing in the United States.

One of those taking part in the demonstration told the Spanish-language US television channel Telemundo, "This is a peaceful protest, we don't want any violence."

Read more: Scale of Mexico's migrant influx 'completely unexpected'

Trapped between the cartels and razor wire

In January, the US enacted a policy known as Migrant Protection Protocols (MPP), which sent migrants back to Mexico to await asylum processing. That process can take months, if not years.

More than 51,000 individuals have been sent back to Mexico under MPP, with at least 800 being sent to Matamoros, a city infamous for gang violence and cartel-controlled human trafficking.

Read more: For Honduran migrants, leaving home is an uphill battle

Tens of thousands waiting to get into the US

In July, the Associated Press news agency reported that some 19,000 asylum seekers had registered on waiting lists in Matamoros and three other cities along the border. They have been forced to wait there for weeks and months — sleeping in tents and on the streets — due to the backlog created by a US policy known as metering, in which the US only allows a handful of people to cross the border each day.

Many of those seeking asylum in the US are not from Mexico, but rather from crisis-ridden Central American countries such as El Salvador, Guatemala and Honduras.

In September, the US Supreme Court upheld a policy put forth by the Trump administration, allowing it to deny asylum to anyone who passes through a third country en route to the US without requesting asylum in that country.

The decision therefore affects almost everyone arriving at the US' southern border.

In pictures: Photojournalist wins top award for portrayal of migrant caravan Award-winning photojournalist highlights migrant crisis Throughout 2018 and 2019 thousands of Central American's headed north, hoping to cross the US border in search of a better life. Guillermo Arias won a prestigious photojournalism award documenting their dangerous journey.

In pictures: Photojournalist wins top award for portrayal of migrant caravan Seeking asylum with children Parents who are seeking asylum in the United States often bring their children, under the belief this will support their application. However, families face harsh treatment at the border with sometimes even very young children being separated from their parents and placed in detention camps alone.

In pictures: Photojournalist wins top award for portrayal of migrant caravan Migrants walk thousands of miles for a better life The journey for the migrants to reach the US border is dangerous and could take weeks. Those that decide to join the caravans come from countries such as Honduras, Guatemala, Nicaragua and El Salvador. They are prepared to walk up to 2,000 kilometers (1,242 miles), as well as boarding trucks and trains to flee criminal violence in their home countries and seek a better life in the US.

In pictures: Photojournalist wins top award for portrayal of migrant caravan Mexico feels the strain of the migrant caravans Migrants help a child catch a ride on a truck on the road linking Sayula de Aleman and Isla, Veracruz state, Mexico. Mexico continues to be a very important migration corridor as many migrants think it would now be easier to enter the US via Mexico.

In pictures: Photojournalist wins top award for portrayal of migrant caravan Help is at hand for migrants in Mexico The sheer numbers of migrants headed toward the US is a huge strain on Mexico, and coping requires considerable resources and coordination. Mexico's policy towards the migrants has become much more lenient and the country now offers medical care and access to education for their children.



js/dr (AP, dpa, Reuters)