Generally, First-Class Mail takes between 1 to 3 business days for delivery within the contiguous United States. This means that if you mail a letter or package from Vermont to Boston on Monday, it is likely to be delivered by Wednesday or Thursday of the same week.
However, there are some factors that can affect the delivery time. For example, if the mail is being sent to a rural or remote area, it may take an extra day or two for delivery. Additionally, if the mail is sent during a busy period, such as the holidays, it may experience delays.
You can visit the USPS website or contact your local post office for more information on the specific delivery times for your area.