Among the prestigious American universities, Harvard University has the most challenging admission rate, with an acceptance rate of just 5.2% and SAT scores ranging from 1430 to 1600 (according to Niche.com).

This ranking is based on acceptance rates and SAT/ACT scores from the U.S. Department of Education in 2017. Acceptance rates account for 60% and SAT/ACT scores account for 40% of the ranking criteria.
Here are the rankings of the most “challenging” universities to get into in the United States:

Acceptance rate: 9%
SAT: 1320-1490

Acceptance rate: 13%
SAT: 1305-1530

Acceptance rate: 13%
SAT: 1400-15670

Acceptance rate: 15%
SAT: 1410-1570

Acceptance rate: 11%
SAT: 1400-1560

Acceptance rate: 9%
SAT: 1340-1540

Acceptance rate: 13%
SAT: 1420-1580

Acceptance rate: 11%
SAT: 1350-1560

Acceptance rate: 11%
SAT: 1380-1570

Acceptance rate: 9%
SAT: 1380-1570

Acceptance rate: 9%
SAT: 1370-1570

Acceptance rate: 11%
SAT: 1420-1590

Acceptance rate: 7%
SAT: 1410-1590

Acceptance rate: 8%
SAT: 1450-1600

Acceptance rate: 7%
SAT: 1400-1590

Acceptance rate: 8%
SAT: 1510-1600

Acceptance rate: 8%
SAT: 1460-1590

Acceptance rate: 6%
SAT: 1420-1600

Acceptance rate: 5%
SAT: 1380-1580

Acceptance rate: 5%
SAT: 1430-1600
Source: https://www.msn.com/en-us/money/careersandeducation/the-20-hardest-colleges-to-get-into-in-america/ss-AAx7XZR?ocid=spartandhp#image=1