The Pacific Ocean.
Washington borders Idaho to the east and and Oregon also borders Idaho to the east.
Idaho borders Oregon from the east.
Suriname borders Guyana to the East.
Kansas borders the east of Colorado.
The Atlantic Ocean borders east of Florida.
Oman borders Yemen to the east.
The Atlantic Ocean borders the US to the East. The Pacific Ocean borders the western side.
The Atlantic Ocean borders the United States to the east.
Lithuania borders Kaliningrad to the north and east.
The Sea of Japan borders North Korea to the east.
the state that borders Arizona to the east is New Mexico
No state borders Maine to the east, instead it it just the vast Atlantic ocean.