By Catherine E. Shoichet and Natalie Gallón, CNN

(CNN) -- US President Donald Trump has pointed to a massive caravan of migrants trekking north through Mexico as a major issue in the upcoming midterm elections.

But when Election Day rolls around on November 6, the caravan could still be somewhere in the middle of Mexico, depending on the group's current location, how fast it's been traveling and how long it's taken other groups of migrants to cross the country.

On Thursday morning, the caravan of thousands of people left Mapastepec, Mexico, about 80 miles from the Mexico-Guatemala border, where many of the caravan's members skirted authorities and crossed in rafts.

The group is hoping to get to the town of Pijijiapan, about 30 miles away, by the end of the day.

It's still too soon to know exactly where along the vast US-Mexico border the bulk of this caravan will travel.

The group formed in Honduras nearly two weeks ago and only crossed into Mexico on Friday.

And they may not be the only ones headed north: other caravans in Central America appear to be following in their footsteps.

Members of the caravan that formed in Honduras are charting their movement daily.

Organizers have told CNN they still don't know exactly which route they'll take. Much depends on the Mexican government and what routes the caravan is allowed to travel, whether its members are detained or held in certain areas and whether the group is provided with buses to speed their journey.

There's a possibility some members will split off and try to make their own way to the US-Mexico border. Others have decided to stay in Mexico -- or return to their home countries.

The safest route would take them to Tijuana, across the US border from San Diego. A large caravan that crossed Mexico in the spring -- and also drew ire from President Trump -- took more than 30 days to reach Tijuana from Tapachula, Mexico -- a city this caravan departed on Monday.

Right now the closest border crossing to this caravan would be between Matamoros, Mexico, and Brownsville, Texas, more than 1,000 miles away from the group's current location. But heading that way is considered a more dangerous route.

To date, the caravan has traveled about 20-30 miles a day, trekking largely on foot and also hitching rides on passing vehicles when possible. If it continues at that rate, reaching Tijuana could take months, and reaching Matamoros could take weeks.

The Mexican government estimates about 3,600 people are heading north. The caravan's organizers and international aid groups, including UNHCR, have said more than 7,000 people make up the group.

Mexican authorities say they've begun processing asylum requests for more than 2,700 Central Americans who arrived with this caravan. And nearly 500 more Hondurans have voluntarily agreed to return to their home country, Mexican officials said.