Preheat oven to 325 degrees. Butter two 5-by-9-inch loaf pans. Combine all-purpose flour and salt in a bowl.
Cream butter and sugar with a mixer on high speed until pale and fluffy, for 8 minutes. Scrape down sides of bowl. Reduce speed to medium, and add vanilla extract.
Lightly beat eggs, and add to mixer bowl in 4 additions, mixing thoroughly after each and scraping down sides. Reduce speed to low, and add flour mixture in 4 additions, mixing until just incorporated. Divide batter between pans. Tap on counter to distribute; smooth tops.
Bake until a tester inserted into center of each cake comes out clean, about 65 minutes. Let cool in pans on a wire rack for 30 minutes. Remove from pans, and let cool completely on wire rack.