Answer:
on what could you send it more clearly I can't see
As for the rivers, the colonists were aware you must have water to successfully maintain life whether it be human life or plant life, it is necessary. Also being close to water helped them in the workforce, like carrying out trade or fishing It was a "win win" for them.
According to Graham Allison book, Nuclear Terrorism, only 5 percent of daily cargos into the U.S are screened where every day 30,000 trucks, 6500 rail cars and 140 ships deliver over 50,000 cargo containers into the United States. This rarely involves physical inspection which may not detect nuclear weapons and fissile materials.
