US Immigration - 30day AVR (Automatic Visa revalidation) after leaving US

Automatic revalidation (contiguous territory rule):

1. All valid H1B, H4, L,F,J visa holders with expired visa stamps in their passports who went outside the U.S. for travel to Canada, Mexico for 30 days or less are eligible to re-enter the USA without getting a new visa stamp. 
2. Automatic revalidation is not available if you are going for visa stamping in Canada or Mexico. 
3. There should be no pending visa application at the time of re-entry to make use of the ‘Automatic Revalidation’ process.
   
4. Automatic revalidation is also allowed in case you change your visa status after entering the US territory on some other visa.
5. You cannot enter the USA using the AVR process if your visa application is pending with the US embassy in Canada or Mexico.
6. if you have applied for a new visa while in Canada or Mexico, or are a citizen or national of Cuba, Iran, North Korea, Sudan, or Syria, you will not be accorded automatic revalidation and consequently will not be readmitted to the United States without obtaining a new visa abroad.
7. If the visa stamp is denied or is pending for form 221g or DS 5535 processing with the US embassy, you cannot use the automatic visa revalidation rule. If you are still allowed then it may pose future issues at the time of your green card processing.
   
8. Once you use the Automatic Visa Revalidation process, the old expired visa is considered valid only up to that date and day.
9. An expired nonimmigrant visa may be "automatically" extended to the date of reapplication for admission when a foreign national has made a trip of 30 days or less in duration to Canada or Mexico (or, in the case of a qualified F or J student or exchange visitor, to Canada, Mexico, or adjacent island other than Cuba) and is applying to be readmitted to the United States to resume nonimmigrant status. Where the individual's original nonimmigrant classification has been changed to another nonimmigrant classification, an expired or unexpired visa is automatically extended to the date of application for readmission, and the visa is converted to the new classification.
10. A foreign national who has applied for a new visa while in a nearby country will not be able to obtain automatic revalidation.
11. The applicant will not be permitted to reenter the United States until all security checks pursuant to the application have been completed and the new visa has been issued.
12. Individuals who are nationals of countries identified as state sponsors of terrorism are ineligible for automatic revalidation; currently, these countries are North Korea, Iran, Sudan, and Syria.
13. NOTE: Puerto Rico & US virgin islands are both US territories and travel from US mainland airport to their domestic terminals is considered as domestic travel. No new i94 is issued. US driving license can be used as ID. At minimum a valid i20 or i797 is required.

To qualify for the automatic extension, the foreign national must:

1. 1. Possess a Form I-94 Arrival-Departure Record showing an unexpired period of initial admission or extension of stay.  A qualified F or J student or exchange visitor must have a current Form I-20 Certificate of Eligibility for Nonimmigrant Student Status or Form DS-2019 Certificate of Eligibility for Exchange Visitor Status, endorsed by the issuing school or program to indicate the period of stay authorized by USCIS.
   2. Have maintained and intend to resume nonimmigrant status.
   3. Apply for readmission after an absence from the United States of 30 days or less.
   4. Apply for readmission to the United States within the authorized period of initial admission or extension of stay.
   5.  Possess a valid passport.
   6. Have traveled to a contiguous territory within North America.  
   7. In the case of a student (F) or exchange (J) visitor, the travel must have occurred to a contiguous territory within North America or to any of the following islands:
      
      AVR applicable adjacent islands:

1. Saint Pierre
2. Miquelon
3. The Dominican Republic
4. Haiti
5. Bermuda
6. The Bahamas
7. Barbados
8. Jamaica
9. The Windward and Leeward Islands
10. Trinidad
11. Martinique
12. Other British, French, and Netherlands territories or possessions in or bordering on the Caribbean Sea

References:

Do I need a valid visa to return from a trip of 30 days or less to Canada or Mexico? | Fragomen, Del Rey, Bernsen & Loewy LLP

https://www.am22tech.com/automatic-revalidation-visa-usa/

https://www.am22tech.com/us-visa-travel-puerto-rico/

https://www.fragomen.com/migrated-sitemap-pages/know-your-obligations.html