My Assignment is to set up and solve a system of equations to generate the coefficients of a quadratic (degree 2) interpolating polynomial for the population of Nebraska in the years 1900, 1950, and 2000 was 1,066,000, 1,326,000, and 1,713,000, respectively.

What does this error mean and how do I fix it?
LinearSolve::lslc: Coefficient matrix and target vector(s) or matrix do not have the same dimensions. >>

MatrixForm[ A = {{1, 1900, 1900^2}, {1, 1950, 1950^2}, {1, 2000, 2000^2}}]
MatrixForm[b = {{1066000, 1326000, 1713000}}]
x = LinearSolve[A, b]
then I get the error