The State Department's adjusted refusal rate for visitor (B) visas in FY2025 was 32.8% for Colombia, the highest of these 6 big countries, and 7.5% for Argentina, the lowest.
All 6: Colombia 32.8%; India 22%; Mexico 21.4%; China 20.2%; Brazil 14.9%; Argentina 7.5%. About 67% of Colombia applicants were approved, against about 93% for Argentina.
A refusal rate is a group figure for one year. It cannot tell what will happen to one person, and each case is decided on its own facts. Source: U.S. State Department. Unofficial.
See more: all refusal rates and the visitor visa guide.