The influence the Spanish had on Mexico was significant, beginning with the conversion of much of the local population to Catholicism. However soon after this conversion, the people weren't treated as equals so much as being treated like slaves as the Spanish began ruthlessly exploiting the local populations.
As chaos ensued in Europe, particularly war with France and Napoleon's eventual takeover of Spain, tensions rose in Mexico as the different groups fought over power until 1810 when Padre Miguel Hidalgo launched a rebellion for independence. After 11 years of fighting, Mexico won independence. However, from 1821 until the 1860 Mexico's political stability was non-existent and they were continuously invaded as they failed to control their lands.
Beginning in 1866 Mexico undertook a number of changes including greater access to education, better transportation networks, and improved healthcare, but during this time, free elections were stopped and in 1910 the Mexican Revolution broke out to remedy this, but not without first killing nearly15% of the country and destroying any stability the government once held.
From 1920 until today Mexico has been under strict government rule and the people have hardly had a chance at a fair election or any freedoms at all. This has caused emigration, particularly to the United States a growing concern for both Americans and Mexican alike.