In 1800 the arrondissements of Blois, Romorantin and Vendôme were established. The arrondissement of Romorantin was disbanded in 1926, and restored in 1943.[5] In 2007 the arrondissement of Blois lost the canton of Saint-Aignan to the
arrondissement of Romorantin-Lanthenay.[5]
The borders of the arrondissements of Loir-et-Cher were modified in January 2017:[6]
17 communes from the arrondissement of Blois to the arrondissement of Romorantin-Lanthenay
two communes from the arrondissement of Blois to the arrondissement of Vendôme
three communes from the arrondissement of Romorantin-Lanthenay to the arrondissement of Blois
four communes from the arrondissement of Vendôme to the arrondissement of Blois
In January 2019 the commune
Courmemin passed from the arrondissement of Blois to the arrondissement of Romorantin-Lanthenay.[7]