Actual trip details different from visa application

Aruna writes, "When I applied for a tourist visa at the American Consulate, I was planning to go to Dallas, Texas to attend the wedding of my cousin, and that is the information I provided in my B1/B2 visa application along with details on the dates.  It turns out that due to a family tragedy, I cannot attend the wedding but will instead take a trip with the couple to see the Grand Canyon and Las Vegas a month later than the original plan.  Is this a problem?  My trip dates are different and I will now be spending a week longer than the original plan of 10 days.  What should I do?"

When the State Department asks for an itinerary and purpose of visit it is merely trying to collect some basic information to decide whether a visa should be issued or not.  Everyone understands that plans change so it will not be an issue.  It is also important to understand that the immigrant agent at the airport you will encounter will not immediately have access to your visa application, so the questioning will be along the lines of your trip duration, destination, etc.  If you are asked to go for secondary questioning or the officer asks questions related to your initial plans, you can simply explain exactly what happened.  Remember that if it is a multiple entry visa, you are eligible to use it to visit as many times as you feel like for purpose of business or leisure (a visitor visa is not to be used to live in America but you can have almost unlimited trips in an year to USA).