ypsilanti ( ), commonly shortened to ypsi, is a city in washtenaw county in the u.s. state of michigan. it is known as the home of eastern michigan university. as of the 2010 census, the city's population was 21,018. ypsilanti is located 6 miles (10 km) east of ann arbor and about 18 miles (29 km) west of the detroit city limits.