DETROIT -- Rain, snow or sleet won't stop the mail but economic challenges and tight budgets can change how mail is delivered.

The postal service said it is in the process of surveying more than 4,000 urban and rural mail routes in southeast Michigan and expects to shift mail carrier assignments and delivery times to save money.

The Postal Service plans to make changes on the following dates in these metro Detroit areas:

Jan 5 -- Utica and Shelby Township

Jan. 12 -- Macomb Township and Auburn Hills

Jan. 13 -- Dearborn Heights and Lincoln Park

Jan. 20 -- Oak Park, Riverview, Southgate, Wyandotte and three postal areas of Detroit

Jan. 26 -- Birmingham, Clawson and Sterling Heights

Jan. 27 -- Brighton, Dearborn, Flat Rock, Grosse Ile, Highland Park, Rockwood and six postal areas of Detroit