When was US post office created?

Technician a says that the sine with dwell (swd) test is used to determine if an electronic stability control system functions normally. technician b says that the esc lamp, called a telltale light, is required to remain on for two minutes. who is correct?

What is the name for the main idea behind the settling of western lands by americans in the early-1800s?

What does the term “escalation” refer to?