Consider using visuals
While government pamphlets and similar items intended for the public usually include photos and illustrations, visuals rarely appear in letters or regulations. However, even in these documents, you can use illustrations to good effect. Consider these examples from regulations.
Federal Aviation Regulations in 14 CFR part 95 contain illustrations of mountainous areas which are subject to special flight restrictions, such as this illustration of mountainous areas of Alaska:
National Park Service regulations at 36 CFR part 7.96 includes pictures of areas in Washington, DC, where activities are controlled, such as these drawings of the White House and Lincoln Memorial:
14 CFR 1221.102 establishes the NASA Seal.
Appendix C to 40 CFR Part 50 illustrates the measurement principle and calibration procedure for measuring carbon monoxide in the atmosphere.
50 CFR section 216.95 illustrates the official mark for “Dolphin-safe” tuna products.