GLMZ receives an estimated 340,000 climate and conflict refugees per year, arriving primarily through the southern overland routes from the Gulf Coastal Exclusion Zone, the collapsed agricultural regions of the Central Basin, and the flooded delta communities of the lower Mississippi system. The legal framework governing their status is the Meridian Regional Habitability and Migration Ordinance of 2177, which was drafted during a period of peak political anxiety about population pressure and reflects that anxiety in almost every provision. The Ordinance does not use the word 'refugee' — it uses 'Unscheduled Arrivals,' a classification that carries no legal protections under international frameworks that the megacity's governance structure has effectively opted out of.

Upon arrival, Unscheduled Arrivals are processed through one of four Intake Assessment Facilities: the Calumet South Facility, the Waukegan Northern Gateway, the Hammond Industrial Transit Hub, or — for those arriving by water — the Lake Michigan Arrival Staging Area, a floating processing platform anchored 4 kilometers offshore that civil liberties organizations have called a detention facility in all but name. Processing determines whether an Arrival is granted Provisional Citizenship status, placed on a 'Sponsored Arrival Track' under a corponation labor agreement, or classified as an 'Inadmissible Presence' subject to relocation. The average processing time is 19 days, during which individuals are held in the facility with limited legal access.

The Sponsored Arrival Track is the pathway most commonly offered to individuals assessed as having labor-valuable skills or physical attributes. Under this track, a corponation agrees to sponsor the individual's Provisional Citizenship application in exchange for a Structured Service Agreement — meaning the price of legal status is an indenture commitment averaging 4.8 years before the citizenship application can be filed independently. The arrangement is technically voluntary, since the alternative is Inadmissible Presence classification, which carries relocation to one of three Meridian Regional Dispersal Sites outside the megacity's boundaries. The largest of these, the Kankakee Transitional Settlement, houses approximately 180,000 people in conditions that a 2198 UN Monitoring Group report described as 'incompatible with minimum standards of human dignity' — a report that Meridian's Civic Assembly received and tabled without debate.

Legal advocacy for Unscheduled Arrivals is provided almost exclusively by the Meridian Arrivals Solidarity Network, an NGO coalition operating out of three offices in the Pilsen Corridor and the Bridgeport Transitional District. The Network's legal team of 22 attorneys handles approximately 3,000 cases per year. They have won Provisional Citizenship status for 847 individuals since 2193 and have successfully challenged 12 Inadmissible Presence classifications. They have never won a case against a Sponsored Arrival Track SSA, because the courts have consistently held that the agreement was entered into voluntarily at the point of processing.