If you are making a trip outside the United States, to re-enter the US, you will need the following:
If you have changed your nonimmigrant status to H1B, O1 or E3 while in the United States and have never had an H1B, O1 or E3 visa stamp in your passport, or if your visa stamp has expired, you must make an application with a US Embassy or Consulate outside of the US to obtain an H1B, O1 or E3 visa for re-entry.** For will need to present the following documentation:
Please note that if you are a Canadian citizen, you do not have to apply for and obtain a visa stamp in your passport. At the port of entry, you can simply show your Canadian passport and H1B documentation listed above in order to be admitted in H1B immigration status for Cornell University employment.
If you have an visa stamp and it has expired, you must apply for the renewal of the visa stamp in the same way that you applied for the initial visa stamp in person at a US Embassy or Consulate abroad (see information above). It is not possible to obtain a US visa stamp within the US.
If you have an expired H1B, O1 or E3 visa stamp or if you have an expired U.S. non-immigrant visa of any other type (e.g. B, F, J) and you have a valid I-94 card stating your current valid H1B, O1 or E3 status, your visa will be considered automatically revalidated when you re-enter the U.S. from Canada or Mexico as long as ALL of the following are true:
For this automatic revalidation to apply to you, you must be careful to keep your I-94 card when leaving the US to enter Canada or Mexico for a trip of less than 30 days. Present your I-94 card along with your valid passport, original Form I-797A (H1B or O1 Approval Notice) or, if E3, LCA (ETA 9035) and a letter from your hiring department/unit confirming current employment.
H4, O3 and E3D spouses and minor children must also meet the above passport and visa requirements and show proof of family relationship (marriage certificate or birth certificate) for re-entry to the US. If they are not accompanied by the H1B, O1 or E3, they must have copies of their spouse or parent's I-94 card and approval documents Form I-797A (if H1B or O1) or LCA; ETA 9035 (if E3).