Some states require the use of a specific security instrument, meaning a Deed of Trust or a Mortgage Agreement.
Idaho and Washington, D.C. require the use of a trust deed.
Connecticut, Delaware, Florida, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Nebraska, New Jersey, New Mexico, North Dakota, Ohio, Pennsylvania, and South Carolina require the use of a Mortgage Agreement.
The rest of the states may use one or the other.