650 miles
they are roughly 30 miles aparty OwO.
Distances vary, but the goal was to keep them one day's journey apart from each other. From the southernmost (Mission San Diego de Alcala in San Diego) to the second-southernmost (Mission San Luis Rey in Oceanside), the distance is just under 40 miles. From there to the San Juan Capistrano Mission (Geographically Number 3 in the series) is another 32 miles. From there to the San Gabriel Mission (Number 4) is just under 60 miles. From there to the Mission at San Fernando (Number 5) is about 30 miles.
Traditionally they are a days ride distance from each other. In the 1800's that would have been 30-40 miles apart.
Each of the missions are a days ride from each other. This is about 30-40 miles apart for each of the 21 missions. San Diego was an important Spanish settlement and when Mexico took over it was still important so a mission there was an important part of the society and government.
All of the missions were founded to bring the Catholic religion to people, to have a settlement and establish a foothold in the area. Each mission was 30-40 miles apart a days ride apart so there was a stopping point.
4,790 miles long
They are about 372 miles away from each other.
The shortest said distance would make these two cities around 121 miles apart from each other.
Fourty miles away from each other
I assume you are asking about the California missions. Just about each mission has the original buildings. The state does do reconstruction and repair on each mission.
they are each 90 miles apart
On January 12, 1777 Padre Thomas Peña, under the direction of Padre Junípero Serra, officially founded Mission Santa Clara de Asís, the eighth of California's twenty-one missions. Located along El Camino Real, the Royal Road, these missions stretched up the California coast from San Diego to Sonoma, a distance of about seven hundred miles. When the chain was completed each mission lay about one day's journey by horse apart from the next.
All of the 21 missions were built a days ride from each other which would be about 30-40 miles apart. Santa Cruz was in a good location, had Ocean access, and with plenty of other resources. It established the foothold in the area to build the mission.