The production sourced around 150 vintage motor cars, dating from 1918 to 1928, from collectors throughout Southern California. In some cases the cars were in too good a condition, so the crew modified them to make the cars appear like they were in everyday use; they sprayed dust and water onto the bodywork, and to "age" some of the cars they applied a coating that simulated rust and scratches. The visual effects team retouched shots of Los Angeles City Hall—on which construction was completed in 1928—to remove weathering and newer surrounding architecture. Costume designer Deborah Hopper researched old Sears department store catalogs, back issues of "Life" magazine, and high-school yearbooks to ensure the costumes were historically accurate. Hopper sourced 1920s clothing for up to 1,000 people; this was difficult because the fabrics of the period were not resilient. She found sharp wool suits for the police officers. The style for women of all classes was to dress to create a boyish silhouette, using dropped waist dresses, cloche hats that complemented bob cut hairstyles, fur-trimmed coats and knitted gloves. Jolie said the costumes her Collins character wore formed an integral part of her approach to the character. Hopper consulted historians and researched archive footage of Collins to replicate her look. Hopper dressed Jolie in austere grays and browns with knitted gloves, wool serge skirts accompanying cotton blouses, Mary Jane shoes, crocheted corsages and Art Deco jewelry. In the 1930s sequences at the end of the film, Jolie's costumes become more shapely and feminine, with a decorative stitching around the waistline that was popular to the era.