Mexico to United States.
Texas, New Mexico, Arizona, and California all share a border with Mexico, the only Spanish-speaking country that borders the US.
The only country sharing a border with Portugal, that is, Spain
The US states that border Spanish-speaking countries are California, Arizona, New Mexico, and Texas. These states share borders with Mexico.
Portugal, and France are countries that border Spain and do not speak Spanish. Spain also has international borders with the United Kingdom at Gibraltar, and with Morocco at the Spanish Autonomous Cities of Ceuta and Melilla in Africa. Neither Morocco nor the UK are Spanish speaking countries.
Spain and Portugal. The legacy is that whole od the Americas , south of the USA/Mexico border is Spanish speaking, except for Brazil ,which is Portuguese speaking.
Mexico
Spain is the border of Portugal. If you are looking at a map, it'll be on your right, and the maps left.
California, Arizona, New Mexico, and Texas are the US states on the border with Mexico.
Brazil. Another answer could be Paraguay, although it does not directly border Uruguay.
Spain is the only country to border Portugal. Spain is on two sides of Portugal, with the west and south side being the Atlantic Ocean. Spain
Spain is the only country to border Portugal to the east.